Use SDL to set video modes, get a GL context and detect the
amount of VRAM.
As with the Linux GLimp implementation, sys_videoRam can be used
in case the SDL detection fails.
Use SDL_main on all platforms.
Fix main() for non-const argv so it matches with the SDL
prototype.
Adapt win32 WinMain() to main() and get rid of the win32 special
case in Common::Init().
This kills the funky GL logging stubs, which unnecessarily
complicates the build process (think future cmake).
As for logging GL calls: Use apitrace for that
https://github.com/apitrace/apitrace
Let scons link directly in the build folder.
Multiple archs can coexist next to each other.
New scons variable "X86" to cross compile x86 binaries on x86_64.
