[Frontend] Manual re-do of collapse/expand panes

open #90
Major work on new .mini-tab elements, used
as controls to expand/collapse panes;
Cleaned up splitter hover behavior;
Changed mixin controlGrippy to not be tied
to :before;

platform/commonUI/general/res/sass/_icons.scss

@@ -29,6 +29,7 @@
 }
 
 .ui-symbol {
+    font-family: 'symbolsfont';
 	&.type-icon {
 		color: $colorObjHdrIc;
 	}