css6: reduce tree space usage for new theme

The tree has also big space paddings/margins in the crisp theme,
reduce this to a saner level.

www/css/ext6-pve.css

@@ -12,4 +12,14 @@
     color: #fff;
     padding: 4px;
     background-color: #3892d4;
-}
+}
+
+/* reduce tree space */
+.x-grid-cell-inner-treecolumn { /* vertical padding */
+    padding: 4px 0px;
+}
+
+/* horizontal distance between parent and child leaf */
+.x-tree-elbow-img {
+    width: 14px;
+}