Fixes #543.

Only the last layer was being used to determine whether the fragment
shader should apply gamma correction, hue adjustment, etc.  In reality, if
any layer needs it, the fragment shader must do it.
Merge pull request #545 from AnalyticalGraphicsInc/issue543

Fixes #543.
Functions useful for creating bounding spheres from boxes
Added fromArray to Cartesian2 and Cartesian4 for consistency
Added distance to Cartesian2 and Cartesian4 for consistency
Remove whitespace
Update based on review
Merge pull request #548 from AnalyticalGraphicsInc/modelhelpers

BoundingSphere and Cartesian functions
Fix jsHint error.
Merge remote-tracking branch 'origin/master' into oneTexturePerLayer

Conflicts:
	Source/Scene/CentralBodySurface.js