Support room transitions

[tzachshabtay]

No description provided.

[tzachshabtay]

Proposed Algorithm:

1. player.ChangeRoom

Iteration 1
2. Render new scene to Back buffer to texture
3. Copy front buffer to back buffer
4. Assign texture to transition shader

Iteration 2-n
5. Apply transition shader on texture without rendering scene, with time parameter
6. Until time is completed, then unbind shader & texture

Iteration n+1
7. Render new scene as normal