JS: fix multiselect burning resources

Especially on browsers with slow JS like IE8 iterating again and again
over all rows used to harm response rendering. Immagine a dasboard with
a total of a few hundred rows refreshing every 10 seconds while taking
3 secs to render one dashlet... it's far better right now.

refs #6417

public/css/icinga/widgets.less

@@ -38,3 +38,11 @@ table.historycolorgrid a {
 table.historycolorgrid a:hover {
   text-decoration: none;
 }
+
+table.multiselect tr[href] td {
+  user-select: none;
+  -webkit-user-select: none;
+  -moz-user-select: none;
+  -ms-user-select: none;
+}
+

public/js/icinga/events.js

@@ -28,7 +28,6 @@
             this.applyGlobalDefaults();
             this.applyHandlers($('#layout'));
             this.icinga.ui.prepareContainers();
-            this.icinga.ui.prepareMultiselectTables($(document));
         },
 
         // TODO: What's this?

public/js/icinga/loader.js

@@ -412,9 +412,6 @@
 
             this.icinga.ui.initializeTriStates($resp);
 
-            // Make multiselection-tables not selectable.
-            this.icinga.ui.prepareMultiselectTables($resp);
-
             // Replace images with sparklines.
             $resp.find('img.inlinepie').each(function(){
                 self.icinga.ui.initializeSparklines($(this));

public/js/icinga/ui.js

@@ -276,19 +276,6 @@
             */
         },
 
-        /**
-         * Prepare all multiselectable tables for multi-selection by
-         * removing the regular text selection.
-         */
-        prepareMultiselectTables: function () {
-            var $rows = $('table.multiselect tr[href]');
-            $rows.find('td').attr('unselectable', 'on')
-                .css('user-select', 'none')
-                .css('-webkit-user-select', 'none')
-                .css('-moz-user-select', 'none')
-                .css('-ms-user-select', 'none');
-        },
-
         /**
          * Add the given table-row to the selection of the closest
          * table and deselect all other rows of the closest table.