Fix #34875: 0 digits of precision was not supported for FloatProperty, now
you can specify precision=0 for this, and use -1 for the default 2.

git-svn-id: https://svn.blender.org/svnroot/bf-blender/trunk/blender@55910 954f8c5b-7b00-dc11-b283-0030488c597c