Fixes for MSVC (Microsoft Compiler)
MSVC can't link to private methods of ImageMagick since they aren't available, sanpera doesn't use them, it looks like they were only included for completeness.
MSVC can't handle many C99 features including static inside brackets, these now produce warnings, but it doesn't seem to break anything.
Auto-detect ImageMagick path on windows via registry keys.
Demo program working with python3
Updated README to note that CFFI is used not Cython