Blender Git Loki

Ocean Modifier: allow spray maps to be baked

In comments made by a tester on rB17b89f6dacba007bf, it seems that baking
of the spray maps would be useful. This commit adds that capability. Both
the spray map and its inverse are baked out in this change, for maximum
convenience and to avoid assuming what the user wants.

Differential Revision: https://developer.blender.org/D8470