[Frontend] Refinements to .loading and related

#445
Markup enhanced in wait-node.html;
More wait-spinner constants added;
Normalized appearance between tree-based
.loading and .s-status-pending;
Fixed .s-status-pending to work now that
mct-representation is gone from tree;

platform/commonUI/general/res/templates/tree/wait-node.html

@@ -19,4 +19,6 @@
  this source code distribution or the Licensing information page available
  at runtime from the About dialog for additional information.
 -->
-<li class='tree-item t-wait-node loading'>Loading...</li>
+<li class='tree-item t-wait-node loading'>
+    <span class="t-title-label">Loading...</span>
+</li>