add elements to collections via context menu

git-svn-id: svn://svn.code.sf.net/p/vpinball/code/trunk@916 14438d79-0ffd-4333-8ae7-ea2bdd901387
Merge branch 'master' into fixes
Merge branch 'fixes' into dev
Simple optimization for GetSurfaceHeight().
Improved kicker rendering.

Now respects depth buffer, but balls which drop into cup kickers now
look wrong since their lower half is cut off.
Removed some code duplication in Matrix3D.
Merge branch 'fixes' into dev
Started separating elements into transparent and not and sorting the transparent ones.