Webpack 4

Created by: andriijas

• Update to webpack 4.x.x
• Utilize webpack 4 development and production modes
• Upgrade webpack dev server
• webpack 4 compatible release of thread-loader
• webpack 4 compatible release of HtmlWebpackPlugin
• webpack 4 compatible release of SwPrecacheWebpackPlugin
• webpack 4 compatible release candidate of WebpackManifestPlugin
• Update README
• Update WebpackDevServerUtils
• Update InterpolateHtmlPlugin
• Update ModuleScopePlugin
• Update WatchMissingNodeModulesPlugin
• Use optimization.minimizer for custom uglify options
• Use optimization.splitChunks for vendor splitting (https://twitter.com/wSokra/status/969633336732905474)
• create-react-app polyfills included in vendor chunk
• Use optimization.runtimeChunk for long term caching (https://twitter.com/wSokra/status/969679223278505985)
• Remove react-error-overlay is not meant for use in production. warning from dev mode by updating webpack config to proxy process.env.NODE_ENV from ancestor
• Replace ExtractTextPlugin with MiniCssExtractPlugin
• Implicit webpack.NamedModulesPlugin in dev config as its default in webpack 4
• Disable webpack performance hints as we have our own filesize reporter
• Move InterpolateHtmlPlugin to make it tapable on HtmlWebpackPlugin
• Replace ExtractTextPlugin with MiniCssExtractPlugin
• Switch to css whole file minification via OptimizeCSSAssetsPlugin rather than per module css minification to gain performance

Fixes: #3878 (closed)