Better build process (#1248)

* Remove gulp, replace with custom scripts
* Symlink entire dirs where possible (fixes #1232)
* Significantly speed up subsequent builds (fixes #1238)
* Watch process now observes new/removed files, not only changed
* Add ignoreMask, exclude all files with names starting with a #
* Better logging during builds
* Update travis.yml to use new, non-gulp-based build

scripts/copy.js

@@ -0,0 +1,67 @@
+'use strict';
+
+const globby = require('globby');
+const path = require('path');
+const fs = require('fs-extra');
+const { getSignatures, writeSignatures, cleanUp, compareSignatures, getFileSignature, onSuccess, onError, onProgress } = require('./utils');
+const { copyDirs, ignoreMask } = require('./config');
+
+const ROOT = path.resolve(__dirname, '..');
+
+async function getCopy(source, options, signatures) {
+	const t1 = Date.now();
+	const files = await globby(source, Object.assign({ cwd: ROOT }, options ));
+	const totalCount = files.length;
+	var count = 0;
+	var f;
+
+	while ((f = files.pop()) != null) {
+		let newFileSignature = await getFileSignature(f);
+		const dest = path.join('build', f);
+
+		if (f in signatures) {
+			if (compareSignatures(newFileSignature, signatures[f])) {
+				try {
+					await fs.access(dest, fs.constants.F_OK);
+					continue;
+				} catch (_) {
+					// file does not exists in build, fallback to browserifing
+				}
+			}
+		}
+		try {
+			await fs.mkdirp(path.dirname(dest));
+			await fs.copy(f, dest);
+			onProgress(f, dest, 'cp');
+			signatures[f] = newFileSignature;
+			count++;
+		} catch (err) {
+			throw new Error(`Failed on ${f}: ${err}`);
+		}
+	}
+	
+	const t2 = Date.now();
+	return {
+		action: 'copy',
+		count,
+		totalCount,
+		processingTime: t2 - t1
+	};
+}
+
+module.exports = getCopy;
+
+if (require.main === module) {
+	(async () => {
+		try {
+			const signatures = await getSignatures();
+			onSuccess(await getCopy(copyDirs.map(d => `${d}/**`), { ignore: ignoreMask }, signatures));
+			onSuccess(await cleanUp(signatures));
+			await writeSignatures(signatures);
+		} catch (err) {
+			process.exitCode = 1;
+			global.isError = true;
+			onError(err);
+		}
+	})();
+}