Fix developer error when zooming creates an invalid frustum. Also fix crash when attempting to normalize the zero vector during translation in 2D.
Merge branch 'master' into cameraZoom2D

Conflicts:
	CHANGES.md
Add test for clamping zoom in 2D.
Merge branch 'master' into cameraZoom2D
Merge pull request #1437 from AnalyticalGraphicsInc/cameraZoom2D

Fix DeveloperError when zooming in 2D