Convert everything in the Sky API from degrees to radians.

sky/examples/game/lib/transform_node.dart

Index: sky/examples/game/lib/transform_node.dart
diff --git a/sky/examples/game/lib/transform_node.dart b/sky/examples/game/lib/transform_node.dart
index e5bc444001a5de47b3b21fc8d27a34a0692b8585..199ca55f80719ce0d06f337c159b0415f1416fb5 100644
--- a/sky/examples/game/lib/transform_node.dart
+++ b/sky/examples/game/lib/transform_node.dart
@@ -123,7 +123,7 @@ class TransformNode {
     canvas.save();
     
     canvas.translate(_position[0], _position[1]);
-    canvas.rotateDegrees(_rotation);
+    canvas.rotate(degrees2radians(_rotation));
     canvas.translate(-_width*_pivot[0], -_height*_pivot[1]);
     
     // TODO: Use transformation matrix instead of individual calls
@@ -147,4 +147,4 @@ class TransformNode {
   void update(double dt) {
 
   }
-}
+}