Frontent dev env (#247)

* Added frontend development files/environment

* More items-categories related removals

* Improvements in pages templates (inc. static pages)

* Improvements in video player

* Added empty home page message + cta

* Updates in media, playlist and management pages

* Improvements in material icons font loading

* Replaced media & playlists links in frontend dev-env

* frontend package version update

* chnaged frontend dev url port

* static files update

* Changed default position of theme switcher

* enabled frontend docker container

frontend/packages/scripts/lib/webpack-plugins/MyHtmlBeautifyWebpackPlugin.ts

@@ -0,0 +1,74 @@
+/**
+ * @see {link: https://github.com/seeyoulater/html-beautify-webpack-plugin/blob/master/index.js}
+ */
+
+const prettify = require('html-prettify');
+const HtmlWebpackPlugin = require('html-webpack-plugin');
+
+const WebpackError =  require( 'webpack/lib/WebpackError.js' );
+
+import { Compiler, Compilation } from 'webpack';
+
+interface OptionsConfigHtml {
+	end_with_newline: boolean,
+	indent_inner_html: boolean,
+	preserve_newlines: boolean,
+	max_preserve_newlines: number,
+}
+
+interface OptionsConfig {
+	indent_size: number,
+	indent_with_tabs: boolean,
+	html: OptionsConfigHtml
+}
+
+interface Options{
+	config: OptionsConfig,
+	replace: Array<string|RegExp>
+}
+
+interface HtmlWebpackPluginArgs{
+	html: string,
+	plugin: typeof HtmlWebpackPlugin,
+	outputName: string
+}
+
+function htmlPluginDataFunction (pluginData: HtmlWebpackPluginArgs, options: Options, callback: (err:typeof WebpackError, arg1: HtmlWebpackPluginArgs) => void) {
+	
+	pluginData.html = prettify( 
+		options.replace.reduce( (res:string, item: string | RegExp) => res.replace( item instanceof RegExp ? new RegExp(item, 'gi') : item, '' ), pluginData.html )/*,
+		options.config*/
+	);
+
+	callback(null, pluginData);
+}
+
+export default class MyHtmlBeautifyWebpackPlugin {
+
+	apply(compiler: Compiler): void {
+	
+		const options: Options = {
+			config: {	// TODO: Remove it.
+				indent_size: 4,
+				indent_with_tabs: false,
+				html: {
+					end_with_newline: true,
+					indent_inner_html: true,
+					preserve_newlines: true,
+					max_preserve_newlines: 0,
+				}
+			},
+			replace: []
+		};
+
+		function tapAsyncCallback(pluginData: HtmlWebpackPluginArgs, callback: (err:typeof WebpackError, arg1: HtmlWebpackPluginArgs) => void ){
+			return htmlPluginDataFunction (pluginData, options, callback);
+		}
+
+		function tapHookCallback(compilation: Compilation){
+			return HtmlWebpackPlugin.getHooks(compilation).beforeEmit.tapAsync( 'MyHtmlBeautifyWebpackPlugin', tapAsyncCallback );
+		}
+
+		compiler.hooks.compilation.tap( 'MyHtmlBeautifyWebpackPlugin', tapHookCallback );
+	}
+}