Use Premake to generate MSVC projects

The 2008 and 2010 projects in misc are broken. Rather than trying to fix them, and adding 2012 support, it makes more sense to generate them all with Premake.

I've tested this on Windows 7 with 2008, 2010 and 2012, and everything works.

The precompiled SDL binaries in code/libs didn't work correctly, so I'm building SDL from source instead. I removed the files that aren't used by windows to reduce the size (~1MB instead of ~6MB).

64-bit support doesn't work because the asm files that won't build with MASM64. This is beyond my expertise.

premake5.exe is built from the latest development version of premake.
https://bitbucket.org/premake/premake-dev

There's some improvements over the existing MSVC projects:
* debugging works if you set the output path to a working Q3A install (see the top of premake5.lua for details)
* dedicated server
* GLSL files are tied to the build