Add Windows build support.

This requires the Windows binary zip file of GLEW to be downloaded and
unpacked into glew-1.10.0.
Tested using Visual Studio 2013: cmake . then msbuild ALL_BUILD.vcxproj.
Copy the glew dll into the same folder as the Craft.exe file.

Signed-off-by: Pat Thoyts <patthoyts@users.sourceforge.net>