Replace pseudo-private functions with file-scoped functions

Still working on #705, now going through [DynamicScene](https://github.com/AnalyticalGraphicsInc/cesium/tree/master/Source/DynamicScene). I'll add more commits soon.

Six tests fail but I was getting those failures with agi/master as well, I'm on Linux and probably need to update my drivers, so please run the tests on your end when you review. 

If updating drivers doesn't fix the errors I'll report it on the forum.

Cheers.