modularized all source code (#4391)

* modularized all external plugins

* added README.md in plugins

* fixed title

* fixed typo

* relative link to external plugins

* external plugins configuration README

* added plugins link

* remove plugins link

* plugin names are links

* added links to external plugins

* removed unecessary spacing

* list to table

* added language

* fixed typo

* list to table on internal plugins

* added more documentation to internal plugins

* moved python, node, and bash code and configs into the external plugins

* added statsd README

* fix bug with corrupting config.h every 2nd compilation

* moved all config files together with their code

* more documentation

* diskspace info

* fixed broken links in apps.plugin

* added backends docs

* updated plugins readme

* move nc-backend.sh to backends

* created daemon directory

* moved all code outside src/

* fixed readme identation

* renamed plugins.d.plugin to plugins.d

* updated readme

* removed linux- from linux plugins

* updated readme

* updated readme

* updated readme

* updated readme

* updated readme

* updated readme

* fixed README.md links

* fixed netdata tree links

* updated codacy, codeclimate and lgtm excluded paths

* update CMakeLists.txt

* updated automake options at top directory

* libnetdata slit into directories

* updated READMEs

* updated READMEs

* updated ARL docs

* updated ARL docs

* moved /plugins to /collectors

* moved all external plugins outside plugins.d

* updated codacy, codeclimate, lgtm

* updated README

* updated url

* updated readme

* updated readme

* updated readme

* updated readme

* moved api and web into webserver

* web/api web/gui web/server

* modularized webserver

* removed web/gui/version.txt

3 files changed, 234 insertions, 0 deletions

diff --git a/collectors/python.d.plugin/nginx/README.md b/collectors/python.d.plugin/nginx/README.md
new file mode 100644
index 0000000000..007f45c7cc
--- /dev/null
+++ b/collectors/python.d.plugin/nginx/README.md
@@ -0,0 +1,45 @@
+# nginx
+
+This module will monitor one or more nginx servers depending on configuration. Servers can be either local or remote.
+
+**Requirements:**
+ * nginx with configured 'ngx_http_stub_status_module'
+ * 'location /stub_status'
+
+Example nginx configuration can be found in 'python.d/nginx.conf'
+
+It produces following charts:
+
+1. **Active Connections**
+ * active
+
+2. **Requests** in requests/s
+ * requests
+
+3. **Active Connections by Status**
+ * reading
+ * writing
+ * waiting
+
+4. **Connections Rate** in connections/s
+ * accepts
+ * handled
+
+### configuration
+
+Needs only `url` to server's `stub_status`
+
+Here is an example for local server:
+
+```yaml
+update_every : 10
+priority     : 90100
+
+local:
+  url     : 'http://localhost/stub_status'
+  retries : 10
+```
+
+Without configuration, module attempts to connect to `http://localhost/stub_status`
+
+---
diff --git a/collectors/python.d.plugin/nginx/nginx.chart.py b/collectors/python.d.plugin/nginx/nginx.chart.py
new file mode 100644
index 0000000000..09c6bbd37e
--- /dev/null
+++ b/collectors/python.d.plugin/nginx/nginx.chart.py
@@ -0,0 +1,80 @@
+# -*- coding: utf-8 -*-
+# Description: nginx netdata python.d module
+# Author: Pawel Krupa (paulfantom)
+# SPDX-License-Identifier: GPL-3.0-or-later
+
+from bases.FrameworkServices.UrlService import UrlService
+
+# default module values (can be overridden per job in `config`)
+# update_every = 2
+priority = 60000
+retries = 60
+
+# default job configuration (overridden by python.d.plugin)
+# config = {'local': {
+#             'update_every': update_every,
+#             'retries': retries,
+#             'priority': priority,
+#             'url': 'http://localhost/stub_status'
+#          }}
+
+# charts order (can be overridden if you want less charts, or different order)
+ORDER = ['connections', 'requests', 'connection_status', 'connect_rate']
+
+CHARTS = {
+    'connections': {
+        'options': [None, 'nginx Active Connections', 'connections', 'active connections',
+                    'nginx.connections', 'line'],
+        'lines': [
+            ['active']
+        ]
+    },
+    'requests': {
+        'options': [None, 'nginx Requests', 'requests/s', 'requests', 'nginx.requests', 'line'],
+        'lines': [
+            ['requests', None, 'incremental']
+        ]
+    },
+    'connection_status': {
+        'options': [None, 'nginx Active Connections by Status', 'connections', 'status',
+                    'nginx.connection_status', 'line'],
+        'lines': [
+            ['reading'],
+            ['writing'],
+            ['waiting', 'idle']
+        ]
+    },
+    'connect_rate': {
+        'options': [None, 'nginx Connections Rate', 'connections/s', 'connections rate',
+                    'nginx.connect_rate', 'line'],
+        'lines': [
+            ['accepts', 'accepted', 'incremental'],
+            ['handled', None, 'incremental']
+        ]
+    }
+}
+
+
+class Service(UrlService):
+    def __init__(self, configuration=None, name=None):
+        UrlService.__init__(self, configuration=configuration, name=name)
+        self.url = self.configuration.get('url', 'http://localhost/stub_status')
+        self.order = ORDER
+        self.definitions = CHARTS
+
+    def _get_data(self):
+        """
+        Format data received from http request
+        :return: dict
+        """
+        try:
+            raw = self._get_raw_data().split(" ")
+            return {'active': int(raw[2]),
+                    'requests': int(raw[9]),
+                    'reading': int(raw[11]),
+                    'writing': int(raw[13]),
+                    'waiting': int(raw[15]),
+                    'accepts': int(raw[7]),
+                    'handled': int(raw[8])}
+        except (ValueError, AttributeError):
+            return None
diff --git a/collectors/python.d.plugin/nginx/nginx.conf b/collectors/python.d.plugin/nginx/nginx.conf
new file mode 100644
index 0000000000..71c5210669
--- /dev/null
+++ b/collectors/python.d.plugin/nginx/nginx.conf
@@ -0,0 +1,109 @@
+# netdata python.d.plugin configuration for nginx
+#
+# You must have ngx_http_stub_status_module configured on your nginx server for this
+# plugin to work. The following is an example config.
+# It must be located inside a server { } block.
+#  
+# location /stub_status {
+#   stub_status;
+#   # Security: Only allow access from the IP below.
+#   allow 192.168.1.200;
+#   # Deny anyone else
+#   deny all;
+#  }
+#
+# This file is in YaML format. Generally the format is:
+#
+# name: value
+#
+# There are 2 sections:
+#  - global variables
+#  - one or more JOBS
+#
+# JOBS allow you to collect values from multiple sources.
+# Each source will have its own set of charts.
+#
+# JOB parameters have to be indented (using spaces only, example below).
+
+# ----------------------------------------------------------------------
+# Global Variables
+# These variables set the defaults for all JOBs, however each JOB
+# may define its own, overriding the defaults.
+
+# update_every sets the default data collection frequency.
+# If unset, the python.d.plugin default is used.
+# update_every: 1
+
+# priority controls the order of charts at the netdata dashboard.
+# Lower numbers move the charts towards the top of the page.
+# If unset, the default for python.d.plugin is used.
+# priority: 60000
+
+# retries sets the number of retries to be made in case of failures.
+# If unset, the default for python.d.plugin is used.
+# Attempts to restore the service are made once every update_every
+# and only if the module has collected values in the past.
+# retries: 60
+
+# autodetection_retry sets the job re-check interval in seconds.
+# The job is not deleted if check fails.
+# Attempts to start the job are made once every autodetection_retry.
+# This feature is disabled by default.
+# autodetection_retry: 0
+
+# ----------------------------------------------------------------------
+# JOBS (data collection sources)
+#
+# The default JOBS share the same *name*. JOBS with the same name
+# are mutually exclusive. Only one of them will be allowed running at
+# any time. This allows autodetection to try several alternatives and
+# pick the one that works.
+#
+# Any number of jobs is supported.
+#
+# All python.d.plugin JOBS (for all its modules) support a set of
+# predefined parameters. These are:
+#
+# job_name:
+#     name: myname            # the JOB's name as it will appear at the
+#                             # dashboard (by default is the job_name)
+#                             # JOBs sharing a name are mutually exclusive
+#     update_every: 1         # the JOB's data collection frequency
+#     priority: 60000         # the JOB's order on the dashboard
+#     retries: 60             # the JOB's number of restoration attempts
+#     autodetection_retry: 0  # the JOB's re-check interval in seconds
+#
+# Additionally to the above, this plugin also supports the following:
+#
+#     url: 'URL'       # the URL to fetch nginx's status stats
+#
+# if the URL is password protected, the following are supported:
+#
+#     user: 'username'
+#     pass: 'password'
+#
+# Example
+# 
+# RemoteNginx:
+#     name : 'Reverse_Proxy'
+#     url  : 'http://yourdomain.com/stub_status'
+#
+# "RemoteNginx" will show up in Netdata logs. "Reverse Proxy" will show up in the menu
+# in the nginx section.
+
+# ----------------------------------------------------------------------
+# AUTO-DETECTION JOBS
+# only one of them will run (they have the same name)
+
+localhost:
+  name : 'local'
+  url  : 'http://localhost/stub_status'
+
+localipv4:
+  name : 'local'
+  url  : 'http://127.0.0.1/stub_status'
+
+localipv6:
+  name : 'local'
+  url  : 'http://[::1]/stub_status'
+