nicer gl api

- java class name should suffice as namespace
- also use import static gl instance seems to work now with Gwt

vtm-web-js/src/org/oscim/web/client/GwtMap.java

@@ -17,7 +17,7 @@
 package org.oscim.web.client;
 
 import org.oscim.backend.CanvasAdapter;
-import org.oscim.backend.GL20;
+import org.oscim.backend.GL;
 import org.oscim.backend.GLAdapter;
 import org.oscim.core.MapPosition;
 import org.oscim.gdx.GdxAssets;
@@ -42,7 +42,7 @@ public class GwtMap extends GdxMap {
 		GwtGdxGraphics.init();
 		GdxAssets.init("");
 		CanvasAdapter.textScale = 0.7f;
-		GLAdapter.init((GL20) Gdx.graphics.getGL20());
+		GLAdapter.init((GL) Gdx.graphics.getGL20());
 		GLAdapter.GDX_WEBGL_QUIRKS = true;
 		MapRenderer.setBackgroundColor(0xffffff);