start tile & layer id's with standard strings, to avoid funky characters when later these ids are used as parameters

git-svn-id: http://svn.openlayers.org/trunk/openlayers@983 dc9f47b5-9b13-0410-9fdd-eb0c1a62fdaf

tests/test_Tile.html

@@ -23,7 +23,7 @@
         t.ok( tile.size.equals(size), "tile.size is set correctly" );
 
         t.ok( tile.id != null, "tile is given an id");
-        t.ok( tile.id.startsWith(bounds.toBBOX()), "tile's id starts with bbox of bounds");
+        t.ok( tile.id.startsWith("Tile_"), "tile's id starts correctly");
     }