Fix #359 - Introduce build system based on Gulp

- Add Gulp and new dependencies to `package.json`
- Add `gulpfile.js` with four tasks:
    - `tsc`: For building TypeScript sources
    - `bundle`: For bundling JavaScript modules in a monolith
    - `sorcery`: For resolving the source map chains back to the original TypeScript files
    - `build` (`default`): Runs the whole `tsc` → `bundle` → `sorcery` chain
- Clean up `Dockerfile`, since `cpio` is not needed any more
- Clean up not needed dependencies from `package.json`
- Remove `bin/build`
- Update `bin/release` to use `npm run build` instead of `./bin/build`

gulpfile.js

@@ -0,0 +1,87 @@
+const browserify = require('browserify');
+const buffer = require('vinyl-buffer');
+const fs = require('fs-extra');
+const gulp = require('gulp');
+const merge = require('merge-stream');
+const sorcery = require('sorcery');
+const source = require('vinyl-source-stream');
+const sourcemaps = require('gulp-sourcemaps');
+const ts = require('gulp-typescript');
+const tsify = require('tsify');
+
+
+let buildDir = process.env.BUILD_DIR || 'build';
+
+
+/**
+ * Compile TypeScript sources to JavaScript files and create a source map file for each TypeScript
+ * file compiled.
+ */
+gulp.task('tsc', function () {
+  // Remove the lib/ directory to prevent confusion if files were deleted in src/
+  fs.emptyDirSync('lib');
+
+  // Build all TypeScript files (including tests) to lib/, based on the configuration defined in
+  // `tsconfig.json`.
+  let tsProject = ts.createProject('tsconfig.json');
+  let tsResult = tsProject.src().pipe(sourcemaps.init()).pipe(tsProject());
+  let tsc = tsResult.js.pipe(sourcemaps.write('.', {includeContent: false, sourceRoot: ''})).pipe(gulp.dest('lib'));
+
+  // Copy all addons from src/ to lib/
+  let copyAddons = gulp.src('src/addons/**/*').pipe(gulp.dest('lib/addons'));
+
+  // Copy stylesheets from src/ to lib/
+  let copyStylesheets = gulp.src('src/**/*.css').pipe(gulp.dest('lib'));
+
+  return merge(tsc, copyAddons, copyStylesheets);
+});
+
+/**
+ * Bundle JavaScript files produced by the `tsc` task, into a single file named `xterm.js` with
+ * Browserify.
+ */
+gulp.task('browserify', ['tsc'], function() {
+  // Ensure that the build directory exists
+  fs.ensureDirSync(buildDir);
+
+  let browserifyOptions = {
+    basedir: buildDir,
+    debug: true,
+    entries: ['../lib/xterm.js'],
+    standalone: 'Terminal',
+    cache: {},
+    packageCache: {}
+  };
+  let bundleStream = browserify(browserifyOptions)
+        .plugin(tsify)
+        .bundle()
+        .pipe(source('xterm.js'))
+        .pipe(buffer())
+        .pipe(sourcemaps.init({loadMaps: true, sourceRoot: '..'}))
+        .pipe(sourcemaps.write('./'))
+        .pipe(gulp.dest(buildDir));
+
+  // Copy all add-ons from lib/ to buildDir
+  let copyAddons = gulp.src('lib/addons/**/*').pipe(gulp.dest(`${buildDir}/addons`));
+
+  // Copy stylesheets from src/ to lib/
+  let copyStylesheets = gulp.src('lib/**/*.css').pipe(gulp.dest(buildDir));
+
+  return merge(bundleStream, copyAddons, copyStylesheets);
+});
+
+
+/**
+ * Use `sorcery` to resolve the source map chain and point back to the TypeScript files.
+ * (Without this task the source maps produced for the JavaScript bundle points into the
+ * compiled JavaScript files in lib/).
+ */
+gulp.task('sorcery', ['browserify'], function () {
+  var chain = sorcery.loadSync(`${buildDir}/xterm.js`);
+  var map = chain.apply();
+  chain.writeSync();
+});
+
+gulp.task('build', ['sorcery']);
+
+gulp.task('default', ['build']);