Upgraded SlimDX as the previous one is no longer available in nuget
Moved AssImp.NET to ThirdParty directory

It's not from nuget, so won't be restored, and packages is masked out of
git, so can't live there.
Removed python stdlib from project, and copy directly from packages dir

Can't remember why I didn't just do it this way in the first place...
Don't exclude .obj files -- they're meshes!

Should be excluded by directory anyway