Add weback-dev-server with hot/hmr support

* adds `npm start` / `yarn start` script
* starts a webpack-dev-server using the dev config, served on :3333
* hot reloading (HMR) for react/styles, not working for angular code
* new entry `dev.ts` for dynamic imports of CSS theme (ExtractText does
not work with HMR)
* TS loader pipeline moved out of common to add HMR for react
* applied `hot()` to some react containers (that's their new default
 export, named exports remains for testing)
* added sections to README
* updated yarn.lock

scripts/webpack/sass.rule.js

@@ -2,16 +2,16 @@
 
 const ExtractTextPlugin = require("extract-text-webpack-plugin");
 
-module.exports = function(options) {
+module.exports = function (options, extractSass) {
   return {
     test: /\.scss$/,
-    use: ExtractTextPlugin.extract({
+    use: (extractSass || ExtractTextPlugin).extract({
       use: [
         {
           loader: 'css-loader',
           options: {
             importLoaders: 2,
-            url: false,
+            url: options.preserveUrl,
             sourceMap: options.sourceMap,
             minimize: options.minimize,
           }
@@ -23,8 +23,14 @@ module.exports = function(options) {
             config: { path: __dirname + '/postcss.config.js' }
           }
         },
-        { loader:'sass-loader', options: { sourceMap: options.sourceMap } }
+        { loader: 'sass-loader', options: { sourceMap: options.sourceMap } }
       ],
+      fallback: [{
+        loader: 'style-loader',
+        options: {
+          sourceMap: true
+        }
+      }]
     })
   };
 }