add gulp task for less compilation

gulpfile.js

@@ -0,0 +1,24 @@
+// Less configuration
+const gulp = require('gulp');
+const less = require('gulp-less');
+
+gulp.task('less', function(cb) {
+  gulp
+    .src(['themes/compact.less', 'themes/compact_night.less',
+         'themes/light.less', 'themes/night_blue.less', 'themes/night.less'])
+    .pipe(less())
+    .pipe(
+      gulp.dest(function(f) {
+        return f.base;
+      })
+    );
+  cb();
+});
+
+gulp.task(
+  'default',
+  gulp.series('less', function(cb) {
+    gulp.watch(['themes/*.less', 'themes/*/*.less'], gulp.series('less'));
+    cb();
+  })
+);