feat: web client refresh (#1476)

Give the web client a major overhaul.

User-visible highlights include:

* Mobile is now fully supported.
* Added fullscreen support on mobile.
* Better support for dark mode.
* Added mime icons to the torrent list.
* Improved theme consistency across the app.

Maintainer highlights include:

* Updated code to use ES6 APIs.
* No longer uses jQuery UI.
* No longer uses jQuery.
* Use Webpack to bundle the Javascript, CSS, and assets together -- the entire bundle size is now 68K gzipped.
* Added eslint / prettier / stylelint tooling.
* Uses torrent-get's 'table' mode for more efficient RPC calls.

web/webpack.config.js

@@ -0,0 +1,71 @@
+const path = require('path');
+
+const MiniCssExtractPlugin = require('mini-css-extract-plugin');
+const OptimizeCSSAssetsPlugin = require('optimize-css-assets-webpack-plugin');
+const TerserPlugin = require('terser-webpack-plugin');
+const webpack = require('webpack');
+
+const mode = process.env.WEBPACK_MODE || 'production';
+
+module.exports = {
+  devtool: 'source-map',
+  entry: './src/main.js',
+  mode,
+  module: {
+    rules: [
+      {
+        test: /\.s(a|c)ss$/,
+        use: [
+          'style-loader', // create 'style' nodes from JS strings
+          'css-loader', // translate css into commonjs
+          'sass-loader', // compile sass into css
+        ],
+      },
+      {
+        test: /\.css$/i,
+        use: [ 'style-loader', 'css-loader' ],
+      },
+      {
+        test: /\.(png|jpe?g|)$/i,
+        use: [
+          'url-loader',
+        ],
+      },
+      {
+        test: /\.svg$/i,
+        use: [
+          'url-loader',
+          'svgo-loader'
+        ],
+      },
+    ],
+  },
+  optimization: {
+    minimizer: [
+      new TerserPlugin(),
+      new OptimizeCSSAssetsPlugin({
+        cssProcessorPluginOptions: {
+          preset: ['default', { discardComments: { removeAll: true } }],
+        }
+      })
+    ],
+  },
+  output: {
+    filename: 'transmission-app.js' ,
+    path: path.resolve(__dirname, 'public_html'), 
+    sourceMapFilename: 'transmission-app.js.map'
+  },
+  plugins: [
+    new MiniCssExtractPlugin({
+      chunkFilename: '[id].css',
+      filename: '[name].css'
+    }),
+    new webpack.optimize.LimitChunkCountPlugin({
+      maxChunks: 1,
+    }),
+  ],
+  resolve: {
+    extensions: ['.js', '.scss']
+  },
+};
+