:sparkles: Implement Page bundling and image handling

This commit is not the smallest in Hugo's history.

Some hightlights include:

* Page bundles (for complete articles, keeping images and content together etc.).
* Bundled images can be processed in as many versions/sizes as you need with the three methods `Resize`, `Fill` and `Fit`.
* Processed images are cached inside `resources/_gen/images` (default) in your project.
* Symbolic links (both files and dirs) are now allowed anywhere inside /content
* A new table based build summary
* The "Total in nn ms" now reports the total including the handling of the files inside /static. So if it now reports more than you're used to, it is just **more real** and probably faster than before (see below).

A site building  benchmark run compared to `v0.31.1` shows that this should be slightly faster and use less memory:

```bash
▶ ./benchSite.sh "TOML,num_langs=.*,num_root_sections=5,num_pages=(500|1000),tags_per_page=5,shortcodes,render"

benchmark                                                                                                         old ns/op     new ns/op     delta
BenchmarkSiteBuilding/TOML,num_langs=1,num_root_sections=5,num_pages=500,tags_per_page=5,shortcodes,render-4      101785785     78067944      -23.30%
BenchmarkSiteBuilding/TOML,num_langs=1,num_root_sections=5,num_pages=1000,tags_per_page=5,shortcodes,render-4     185481057     149159919     -19.58%
BenchmarkSiteBuilding/TOML,num_langs=3,num_root_sections=5,num_pages=500,tags_per_page=5,shortcodes,render-4      103149918     85679409      -16.94%
BenchmarkSiteBuilding/TOML,num_langs=3,num_root_sections=5,num_pages=1000,tags_per_page=5,shortcodes,render-4     203515478     169208775     -16.86%

benchmark                                                                                                         old allocs     new allocs     delta
BenchmarkSiteBuilding/TOML,num_langs=1,num_root_sections=5,num_pages=500,tags_per_page=5,shortcodes,render-4      532464         391539         -26.47%
BenchmarkSiteBuilding/TOML,num_langs=1,num_root_sections=5,num_pages=1000,tags_per_page=5,shortcodes,render-4     1056549        772702         -26.87%
BenchmarkSiteBuilding/TOML,num_langs=3,num_root_sections=5,num_pages=500,tags_per_page=5,shortcodes,render-4      555974         406630         -26.86%
BenchmarkSiteBuilding/TOML,num_langs=3,num_root_sections=5,num_pages=1000,tags_per_page=5,shortcodes,render-4     1086545        789922         -27.30%

benchmark                                                                                                         old bytes     new bytes     delta
BenchmarkSiteBuilding/TOML,num_langs=1,num_root_sections=5,num_pages=500,tags_per_page=5,shortcodes,render-4      53243246      43598155      -18.12%
BenchmarkSiteBuilding/TOML,num_langs=1,num_root_sections=5,num_pages=1000,tags_per_page=5,shortcodes,render-4     105811617     86087116      -18.64%
BenchmarkSiteBuilding/TOML,num_langs=3,num_root_sections=5,num_pages=500,tags_per_page=5,shortcodes,render-4      54558852      44545097      -18.35%
BenchmarkSiteBuilding/TOML,num_langs=3,num_root_sections=5,num_pages=1000,tags_per_page=5,shortcodes,render-4     106903858     86978413      -18.64%
```

Fixes #3651
Closes #3158
Fixes #1014
Closes #2021
Fixes #1240
Updates #3757

1 files changed, 6 insertions, 5 deletions

diff --git a/source/content_directory_test.go b/source/content_directory_test.go
index 4ff12af8d..9874acec2 100644
--- a/source/content_directory_test.go
+++ b/source/content_directory_test.go
@@ -14,6 +14,7 @@
 package source
 
 import (
+	"path/filepath"
 	"testing"
 
 	"github.com/gohugoio/hugo/hugofs"
@@ -41,21 +42,21 @@ func TestIgnoreDotFilesAndDirectories(t *testing.T) {
 		{"foobar/bar~foo.md", false, nil},
 		{"foobar/foo.md", true, []string{"\\.md$", "\\.boo$"}},
 		{"foobar/foo.html", false, []string{"\\.md$", "\\.boo$"}},
-		{"foobar/foo.md", true, []string{"^foo"}},
-		{"foobar/foo.md", false, []string{"*", "\\.md$", "\\.boo$"}},
+		{"foobar/foo.md", true, []string{"foo.md$"}},
+		{"foobar/foo.md", true, []string{"*", "\\.md$", "\\.boo$"}},
 		{"foobar/.#content.md", true, []string{"/\\.#"}},
 		{".#foobar.md", true, []string{"^\\.#"}},
 	}
 
-	for _, test := range tests {
+	for i, test := range tests {
 
 		v := viper.New()
 		v.Set("ignoreFiles", test.ignoreFilesRegexpes)
 
 		s := NewSourceSpec(v, hugofs.NewMem(v))
 
-		if ignored := s.isNonProcessablePath(test.path); test.ignore != ignored {
-			t.Errorf("File not ignored.  Expected: %t, got: %t", test.ignore, ignored)
+		if ignored := s.IgnoreFile(filepath.FromSlash(test.path)); test.ignore != ignored {
+			t.Errorf("[%d] File not ignored", i)
 		}
 	}
 }