Fix some tests and do some cleanup.

test/parse/constant_buffer.golden

@@ -0,0 +1,14 @@
+(program	
+ (constant_buffer camera
+  [(:= projection float4x4) 
+   (:= view float4x4)])
+
+ (fun vertex vs_main -> float4 (@position)
+  [(:= pos float4 (@position))] 
+  (:= mv float4 (mul camera.view pos)) 
+  (:= mvp float4 (mul camera.projection mv)) 
+  (return mvp))
+
+ (fun pixel ps_main -> float4 (@target)
+  [] 
+  (return (float4 0.5 0.5 0.5 1))))