Housekeeping (#2520)

* enhance(project): Add .prettierrc to project
* chore(deps): Bump dependencies
* chore(view): Improve readability of the search form view
* chore(admin): Improve language used in the customize_register filter docblock
* chore(lint): Lint project assets
* chore(change-log): Improve/prepare the changelog for actual release
* chore(readme): Improve README feature list
* chore(readme): Update README theme directory structure
* chore(readme): Add GitHub sponsors badge
* chore(readme): Clean up various wording
* fix(ci): Fix failing tests
* fix(mix): Add index.php to purgecss scope (Supersedes #2423) (Credit @oxyc)

webpack.mix.js

@@ -14,31 +14,31 @@ require('laravel-mix-copy-watched');
  |
  */
 
-mix.setPublicPath('./dist')
-   .browserSync('sage.test');
+mix
+  .setPublicPath('./dist')
+  .browserSync('sage.test');
 
-mix.sass('resources/assets/styles/app.scss', 'styles')
-   .sass('resources/assets/styles/editor.scss', 'styles')
-   .purgeCss({
-     whitelist: require('purgecss-with-wordpress').whitelist,
-     whitelistPatterns: require('purgecss-with-wordpress').whitelistPatterns,
-   });
+mix
+  .sass('resources/assets/styles/app.scss', 'styles')
+  .sass('resources/assets/styles/editor.scss', 'styles')
+  .purgeCss({
+    extend: { content: [path.join(__dirname, 'index.php')] },
+    whitelist: require('purgecss-with-wordpress').whitelist,
+    whitelistPatterns: require('purgecss-with-wordpress').whitelistPatterns,
+  });
 
-mix.js('resources/assets/scripts/app.js', 'scripts')
-   .js('resources/assets/scripts/customizer.js', 'scripts')
-   .blocks('resources/assets/scripts/editor.js', 'scripts')
-   .extract();
+mix
+  .js('resources/assets/scripts/app.js', 'scripts')
+  .js('resources/assets/scripts/customizer.js', 'scripts')
+  .blocks('resources/assets/scripts/editor.js', 'scripts')
+  .extract();
 
-mix.copyWatched('resources/assets/images/**', 'dist/images')
-   .copyWatched('resources/assets/fonts/**', 'dist/fonts');
+mix
+  .copyWatched('resources/assets/images/**', 'dist/images')
+  .copyWatched('resources/assets/fonts/**', 'dist/fonts');
 
-mix.autoload({
-  jquery: ['$', 'window.jQuery'],
-});
-
-mix.options({
-  processCssUrls: false,
-});
-
-mix.sourceMaps(false, 'source-map')
-   .version();
+mix
+  .autoload({ jquery: ['$', 'window.jQuery'] })
+  .options({ processCssUrls: false })
+  .sourceMaps(false, 'source-map')
+  .version();