Random number generator: replace a bunch of usage of the global random number
generator with a local one. It's not thread safe and will not give repeatable
results, so in most cases it should not be used.

Also fixes #34992 where the noise texture of a displacement modifier was not
properly random in opengl animation render, because the seed got reset to a
fixed value by an unrelated function while for final render it changed each
frame.

git-svn-id: https://svn.blender.org/svnroot/bf-blender/trunk/blender@56073 954f8c5b-7b00-dc11-b283-0030488c597c
Fix a few warnings. One was an actual bug in freestyle where stroke attributes
were not properly interpolated.

git-svn-id: https://svn.blender.org/svnroot/bf-blender/trunk/blender@56074 954f8c5b-7b00-dc11-b283-0030488c597c
Fix crash rendering environment maps.

git-svn-id: https://svn.blender.org/svnroot/bf-blender/trunk/blender@56075 954f8c5b-7b00-dc11-b283-0030488c597c
Fix crash rendering environment maps. I think this freestyle code was not
intended to be here and probably was left over from some earlier code, as
resetting the configuration on render would lead to data loss.

git-svn-id: https://svn.blender.org/svnroot/bf-blender/trunk/blender@56076 954f8c5b-7b00-dc11-b283-0030488c597c