Add glfwSetWindowMonitor

This adds the ability to switch between windowed and full screen modes,
move a full screen window between monitors and update its desired
resolution and refresh rate.

Fixes #43.

src/win32_platform.h

@@ -197,10 +197,6 @@ typedef struct _GLFWwindowWin32
     GLFWbool            cursorTracked;
     GLFWbool            iconified;
 
-    int                 minwidth, minheight;
-    int                 maxwidth, maxheight;
-    int                 numer, denom;
-
     // The last received cursor position, regardless of source
     int                 cursorPosX, cursorPosY;