[Frontend] Layout and positioning fixes for TC controls

open #889
IN PROGRESS
- Smaller font used on range value;
- More space allocated to left and right
for slider range values;
- Style tweaks to slider look;
- Layout and style of datetime inputs
fixed;
- Input error colors fixed, moved to
theme constants;

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

@@ -48,7 +48,7 @@ $uePaneMiniTabW: 10px;
 $uePaneMiniTabCollapsedW: 11px;
 $ueEditLeftPaneW: 75%;
 $treeSearchInputBarH: 25px;
-$ueTimeControlH: (33px, 23px, 15px);
+$ueTimeControlH: (33px, 15px, 15px);
 // Panes
 $ueBrowseLeftPaneTreeMinW: 150px;
 $ueBrowseLeftPaneTreeMaxW: 35%;