shifted tree_grid.css and its icons to wnframework

public/build.json

@@ -42,6 +42,7 @@
 			"lib/public/css/ui/list.css",
 			"lib/public/css/ui/views.css",
 			"lib/public/css/ui/fonts.css",
+			"lib/public/css/views/tree_grid.css",
 		]
 	},
 

public/css/views/tree_grid.css

@@ -0,0 +1,21 @@
+.cell-title {
+	font-weight: bold;
+}
+
+.cell-effort-driven {
+	text-align: center;
+}
+
+.toggle {
+	height: 9px;
+	width: 9px;
+	display: inline-block;
+}
+
+.toggle.expand {
+	background: url("../lib/images/icons/expand.gif") no-repeat center center;
+}
+
+.toggle.collapse {
+	background: url("../lib/images/icons/collapse.gif") no-repeat center center;
+}