rework dojo singleton modules to better work with phpstorm completion (ugh) - declare() is not needed there anyway

remove event.observe from login form (not needed)
load pluginhost via amd

js/CommonFilters.js

@@ -1,7 +1,7 @@
 'use strict'
 /* global __, ngettext */
 define(["dojo/_base/declare"], function (declare) {
-	return declare("fox.CommonFilters", null, {
+	Filters = {
 		filterDlgCheckAction: function(sender) {
 			const action = sender.value;
 
@@ -387,5 +387,7 @@ define(["dojo/_base/declare"], function (declare) {
 			}
 			dialog.show();
 		},
-	});
+	};
+
+	return Filters;
 });