Don't ignore USE_INLINE on Windows
Clean up defines and includes for Windows

1)  Renamed USE_INLINE to PIL_USE_INLINE to avoid conflicts with
    other headers/libraries.

2)  Replace __WIN32__ and WIN32 with _WIN32

3)  Don't define WIN32 when the compiler is MSVC but not on Windows
    Why would you even...

4)  Don't define strcasecmp if you're not even going to use it.

5)  Don't include Windows.h with undefs for compilers newer than
    1998 everywhere.

6)  Don't surpress warnings for MSVC++ 4.0. People still using
    MSVC++ 4.0 deserve it.

7)  Don't include things that are already included in Windows.h
Merge pull request #652 from CounterPillow/windowshfix

Clean up preprocessor cruft for Windows