displace modifier incorrectly had mid-level set as a 'distance' subtyped property.
also change the minimum texture contrast to 0.0 (was 0.01).


git-svn-id: https://svn.blender.org/svnroot/bf-blender/trunk/blender@53799 954f8c5b-7b00-dc11-b283-0030488c597c