Add vc12 solution.

git-svn-id: http://nvidia-texture-tools.googlecode.com/svn/trunk@1391 95f4ed2b-212e-0410-8b90-d31948207fce
Cleanup vc12 project.

git-svn-id: http://nvidia-texture-tools.googlecode.com/svn/trunk@1392 95f4ed2b-212e-0410-8b90-d31948207fce
Fix vc12 build.

git-svn-id: http://nvidia-texture-tools.googlecode.com/svn/trunk@1393 95f4ed2b-212e-0410-8b90-d31948207fce