Convert everything in the Sky API from degrees to radians.

sky/engine/core/painting/Canvas.h

Index: sky/engine/core/painting/Canvas.h
diff --git a/sky/engine/core/painting/Canvas.h b/sky/engine/core/painting/Canvas.h
index b21d8b6a2264418b8a49c76aae401273a34f078f..8a768f2d8d7f998ce61c5edc19239c1179c465fd 100644
--- a/sky/engine/core/painting/Canvas.h
+++ b/sky/engine/core/painting/Canvas.h
@@ -37,7 +37,7 @@ public:
 
     void translate(float dx, float dy);
     void scale(float sx, float sy);
-    void rotateDegrees(float degrees);
+    void rotate(float radians);
     void skew(float sx, float sy);
     void concat(const Float32List& matrix4);