[Frontend] Refinements to Inspector elements, search inputs

open #199
open #279
Treeview indent removed;
Significant refactoring of search classes to generalize
approach to search inputs;

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

@@ -122,6 +122,10 @@
     .holder-elements {
         .current-elements {
             position: relative;
+            .tree-item .t-object-label {
+                // Elements pool is a flat list, so don't indent items.
+                left: 0;
+            }
         }
     }
 }