gulp tasks and nunjucks templating

- reworked nearly all gulp tasks
- added html templating with nunjucks
- replaced some old html files
- started correction of scss and js files according to lint results

source/code/functions.js

@@ -1,3 +1,5 @@
+'use strict';
+
 function setup() {
 	if($('#js_tph').length && full_view_hover) {
 		// $('body').prepend("<div id=\"js_tph\" class=\"layer__hover hover_full_view_change\"></div>");