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

4 files changed, 116 insertions, 0 deletions

diff --git a/libnetdata/url/Makefile.am b/libnetdata/url/Makefile.am
new file mode 100644
index 0000000000..1cb69ed99a
--- /dev/null
+++ b/libnetdata/url/Makefile.am
@@ -0,0 +1,9 @@
+# SPDX-License-Identifier: GPL-3.0-or-later
+
+AUTOMAKE_OPTIONS = subdir-objects
+MAINTAINERCLEANFILES = $(srcdir)/Makefile.in
+
+
+dist_noinst_DATA = \
+	README.md \
+	$(NULL)
diff --git a/libnetdata/url/README.md b/libnetdata/url/README.md
new file mode 100644
index 0000000000..e69de29bb2
--- /dev/null
+++ b/libnetdata/url/README.md
diff --git a/libnetdata/url/url.c b/libnetdata/url/url.c
new file mode 100644
index 0000000000..8a96063a03
--- /dev/null
+++ b/libnetdata/url/url.c
@@ -0,0 +1,79 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+#include "../libnetdata.h"
+
+// ----------------------------------------------------------------------------
+// URL encode / decode
+// code from: http://www.geekhideout.com/urlcode.shtml
+
+/* Converts a hex character to its integer value */
+char from_hex(char ch) {
+    return (char)(isdigit(ch) ? ch - '0' : tolower(ch) - 'a' + 10);
+}
+
+/* Converts an integer value to its hex character*/
+char to_hex(char code) {
+    static char hex[] = "0123456789abcdef";
+    return hex[code & 15];
+}
+
+/* Returns a url-encoded version of str */
+/* IMPORTANT: be sure to free() the returned string after use */
+char *url_encode(char *str) {
+    char *buf, *pbuf;
+
+    pbuf = buf = mallocz(strlen(str) * 3 + 1);
+
+    while (*str) {
+        if (isalnum(*str) || *str == '-' || *str == '_' || *str == '.' || *str == '~')
+            *pbuf++ = *str;
+
+        else if (*str == ' ')
+            *pbuf++ = '+';
+
+        else
+            *pbuf++ = '%', *pbuf++ = to_hex(*str >> 4), *pbuf++ = to_hex(*str & 15);
+
+        str++;
+    }
+    *pbuf = '\0';
+
+    pbuf = strdupz(buf);
+    freez(buf);
+    return pbuf;
+}
+
+/* Returns a url-decoded version of str */
+/* IMPORTANT: be sure to free() the returned string after use */
+char *url_decode(char *str) {
+    size_t size = strlen(str) + 1;
+
+    char *buf = mallocz(size);
+    return url_decode_r(buf, str, size);
+}
+
+char *url_decode_r(char *to, char *url, size_t size) {
+    char *s = url,           // source
+         *d = to,            // destination
+         *e = &to[size - 1]; // destination end
+
+    while(*s && d < e) {
+        if(unlikely(*s == '%')) {
+            if(likely(s[1] && s[2])) {
+                *d++ = from_hex(s[1]) << 4 | from_hex(s[2]);
+                s += 2;
+            }
+        }
+        else if(unlikely(*s == '+'))
+            *d++ = ' ';
+
+        else
+            *d++ = *s;
+
+        s++;
+    }
+
+    *d = '\0';
+
+    return to;
+}
diff --git a/libnetdata/url/url.h b/libnetdata/url/url.h
new file mode 100644
index 0000000000..6cef6d7a84
--- /dev/null
+++ b/libnetdata/url/url.h
@@ -0,0 +1,28 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+#ifndef NETDATA_URL_H
+#define NETDATA_URL_H 1
+
+#include "../libnetdata.h"
+
+// ----------------------------------------------------------------------------
+// URL encode / decode
+// code from: http://www.geekhideout.com/urlcode.shtml
+
+/* Converts a hex character to its integer value */
+extern char from_hex(char ch);
+
+/* Converts an integer value to its hex character*/
+extern char to_hex(char code);
+
+/* Returns a url-encoded version of str */
+/* IMPORTANT: be sure to free() the returned string after use */
+extern char *url_encode(char *str);
+
+/* Returns a url-decoded version of str */
+/* IMPORTANT: be sure to free() the returned string after use */
+extern char *url_decode(char *str);
+
+extern char *url_decode_r(char *to, char *url, size_t size);
+
+#endif /* NETDATA_URL_H */