Fix cmgl so it compiles correctly under Windows.

This includes setting up the correct include directories for numpy
and adding a wrapper around GL/gl.h that includes windows.h first
when under Windows.

src/FoFiX/cmgl.pyx

@@ -25,7 +25,7 @@
 import numpy
 cimport numpy
 
-cdef extern from "GL/gl.h":
+cdef extern from "glwrap.h":
   ctypedef int GLint
   ctypedef unsigned int GLuint
   ctypedef unsigned int GLsizei

src/FoFiX/glwrap.h

@@ -0,0 +1,6 @@
+#ifdef _WIN32
+#include <windows.h>
+#endif
+
+#include <GL/gl.h>
+#include <GL/glu.h>

src/setup.py

@@ -25,6 +25,7 @@
 # FoFiX fully unified setup script
 from distutils.core import setup, Extension
 import sys, glob, os
+import numpy
 from FoFiX import SceneFactory, Version
 
 
@@ -204,7 +205,7 @@ def isSystemDLL(pathname):
   'packages': ['FoFiX', 'FoFiX.midi'],
   'ext_package': 'FoFiX',
   'ext_modules': [
-    Extension('cmgl', ['FoFiX/cmgl.pyx'], libraries=['opengl32' if os.name == 'nt' else 'GL']),
+    Extension('cmgl', ['FoFiX/cmgl.pyx'], include_dirs=[numpy.get_include()], libraries=['opengl32' if os.name == 'nt' else 'GL']),
   ]
 })