Fixes to get sanpera working on windows and python 3.4

Is there anything interesting in the wand branch btw? I haven't tried to merge it.

Anyway I got sanpera working on windows with python 3.4, haven't tested 2.7, but it should work, its's mostly a bunch of small changes. Have not tried 64-bit python.

There's some C99 syntax that MSVC doesn't like (that I don't fully understand either, but it doesn't seem like it breaks anything, I'm sure you used `static` for a reason though.). Some symbols that aren't public in the windows DLLs (but aren't used for anything by sanpera, I don't think)

demo-program.py updated to use the print function and remove extraneous parentheses and commas.

Also autodetect ImageMagick paths based on registry keys.

Finally, sanpera's pretty cool. I was almost ready to switch back to `wand` before I got this working.