Windows recipes and appveyor CI.

NOTE: GEOS takes >30mn to build, and therefore will fail whenever it is updated. To get around this, I've build GEOS on my own machine and uploaded manually. Everything else should work swimmingly. :smile: 

This is for 32-bit Windows only. 64 bit building hasn't yet been tested.
This patch failed to apply when I tried to build geos. Turned out the reason for this was that the version of `CMakeLists.txt` that was downloaded as part of the geos source had trailing whitespace at the end of both these lines, meaning that they did not match to these lines in the patch :expressionless: