3D View properties region / Mesh Displays panel:
* Made overlays use 2 columns, rather than 1 as suggested by Sebastian König in IRC.
* Small tweak to the Normal size button, grey out if unused. 

git-svn-id: https://svn.blender.org/svnroot/bf-blender/trunk/blender@54962 954f8c5b-7b00-dc11-b283-0030488c597c