ENH: Additional tests for new volume mapper

Change-Id: I545dba94bcfbaeea7bd855b3bad83f9b13bc9824
ENH: Added baselines based generated using old volume mapper

Disabled TestGPURayCastCropping1 to be fixed later.

Change-Id: I643d17283ca67104cc0abe52e5079dbb3508616d
Merge topic 'new_volumerenderingtests' into master

7e69bad4 ENH: Added baselines based generated using old volume mapper
52f78f2d ENH: Additional tests for new volume mapper