New matcap collection for default in release. It's now 24 images, ordered
from regular diffuse to more shiny, stone, wax, eflective, glass and two non-realistic ones.

The menu now shows it in 3 rows. I made the previews a bit smaller, 96 pixels,
like the brushes for painting. 

Thanks everyone for submitting pics! I updated the credit file too, but name
from one person is missing still, will be added next.



git-svn-id: https://svn.blender.org/svnroot/bf-blender/trunk/blender@54336 954f8c5b-7b00-dc11-b283-0030488c597c