Move drawing code to it's own module and simplify draw interface

samples/bounce.scm

@@ -5,6 +5,7 @@
 	(engine core)
 	(engine components core)
 	(engine math)
+	(engine drawing)
 	(srfi 1)
 	(srfi 99))
 
@@ -26,13 +27,11 @@
 					(lambda ()
 					  (let ((draw-pos (v+ (position transform)
 							      (circle-2d-center circle))))
-					    ((if (circle-2d-filled? circle)
-						 draw-circle
-						 draw-circle-lines)
-					     (v-x draw-pos)
-					     (v-y draw-pos)
+					    (draw-circle-2d
+					     draw-pos
 					     (circle-2d-radius circle)
-					     (visual-2d-color vis-2d))))))))))
+					     (visual-2d-color vis-2d)
+					     (circle-2d-filled? circle))))))))))
 
 
 (define-record-type <rigidbody-2d>