Fix for the subtype of range_min/max parameters in RNA Freestyle settings.
These parameters specify a distance in Blender units, so PROP_DISTANCE is more appropriate.
Suggested by Bastien Montagne through personal communications, thanks!

git-svn-id: https://svn.blender.org/svnroot/bf-blender/trunk/blender@55930 954f8c5b-7b00-dc11-b283-0030488c597c