Add command to generate CHANGELOG

This forms the basis of the CHANGELOG, but the commits
need to be formatted with the linkify command and sorted
into the various sections.

gulpfile.js

@@ -7,6 +7,7 @@ const concat = require('gulp-concat');
 const replace = require('gulp-replace');
 const pump = require('pump');
 const fs = require('fs');
+const shelljs = require('shelljs');
 
 const paths = {
 	componentsFile: 'components.json',
@@ -173,7 +174,7 @@ function languagePlugins(cb) {
 	});
 }
 
-function changelog(cb) {
+function linkify(cb) {
 	return pump([
 		src(paths.changelog),
 		replace(
@@ -188,10 +189,49 @@ function changelog(cb) {
 	], cb);
 }
 
+const COMMIT_RE = /^([\da-z]{8})\s(.*)/;
+
+function changes(cb) {
+	const tag = shelljs.exec('git describe --abbrev=0 --tags', { silent: true }).stdout;
+	const commits = shelljs
+		.exec(
+			`git log ${tag.trim()}..HEAD --oneline`,
+			{ silent: true }
+		)
+		.stdout.split('\n')
+		.map(line => line.trim())
+		.filter(line => line !== '')
+		.map(line => {
+			const [,hash, msg] = COMMIT_RE.exec(line);
+			return `* ${msg} [\`${hash}\`]`
+		})
+		.join('\n');
+
+	const changes = `## Unreleased
+
+${commits}
+
+### New components
+
+### Updated components
+
+### Updated plugins
+
+### Updated themes
+
+### Other changes
+
+* __Website__`;
+
+	console.log(changes);
+	cb();
+}
+
 const components = minifyComponents;
 const plugins = series(languagePlugins, minifyPlugins);
 
 
 exports.watch = watchComponentsAndPlugins;
 exports.default = parallel(components, plugins, componentsJsonToJs, build);
-exports.changelog = changelog;
+exports.linkify = linkify;
+exports.changes = changes;

package.json

@@ -35,6 +35,7 @@
     "jsdom": "^13.0.0",
     "mocha": "^6.0.0",
     "pump": "^3.0.0",
+    "shelljs": "^0.8.3",
     "yargs": "^13.2.2"
   },
   "jspm": {