Some tweaks and fixes

- Python already defines flags for its' own printf implementation, so
zstring's printf flags need to use different names.
- intrin.h in gl_clock.cpp: Commented out for now, because Windows 8 is
stubborn about letting headers in its' own SDKs be edited and I can't
fix compilation with this file included. May look into it later.
- Copyright and disclaimer needs to be in py_interp.cpp.
- D_DoomInit: Initialize Python as early as possible so we can error out
if Python isn't available for some reason, most likely due to a missing
DLL.
- Do NOT use fastcall for the default calling convention -- We don't
really get much speedup from it at all and it prevents Python from
linking with us.