NOTES (MJH)
* Camera_Angle and Camera_Zoom are ignored by Mode 2.
* Outputted Camera_Look_At is incorrect with Mode 2 when orthographic 
  projection is disabled. Not sure this can be fixed.
* In my opinion, Set_Camera_Angle and Set_Camera_Zoom should disregard 
  Camera_Aspect_Ratio. Instead, Camera_Aspect_Ratio should be handled 
  at other points in the code. However, altering this behavior could 
  affect old scenes.
* Is it even possible to determine the look_at point when you are using 
  Mode 2 and perspective projection?