Added TriangleDrawable.

CSS vector properties now are separated by space instead of comma.
Added offset to ArcDrawable.
Added new background-image and foreground-image functions: rectangle(), triangle(), circle().
Added some new parameters for the UIEditor, also some minor fixes.

--HG--
branch : dev

bin/assets/ui/uitheme.css

@@ -17,7 +17,7 @@ ProgressBar {
 	display-percent: true;
 	vertical-expand: true;
 	filler-padding: 2dp;
-	movement-speed: 32, 0;
+	movement-speed: 32 0;
 }
 
 WinMenu {
@@ -54,7 +54,7 @@ ScrollBar {
 
 Window {
 	window-flags: shadow;
-	buttons-position-offset: -2, 0;
+	buttons-position-offset: -2 0;
 }
 
 Window::title {