Implemented glDrawArraysInstancedBaseInstance, glDrawElementsInstancedBaseInstance, glDrawElementsInstancedBasevertexBaseInstance.

With this change, a number of SuperBible 6 samples start working.
Merge branch 'master' of https://github.com/vMcJohn/vogl
Implement WGL versions of various utility functions.

Provide typedefs for vogl_gl_context, vogl_gl_drawable and vogl_gl_display in vogl_gl_utils.h.
Provide implementations of vogl_has_active_context, vogl_get_current_context, vogl_get_current_display, vogl_get_current_drawable and vogl_make_current and vogl_destroy_context for WGL.

With this, texture capture on Windows appears to be working.
Add WGL support in _is_swap_buffers and _is_make_current utilities.
Merge pull request #5 from grahamsellers/master

Multiple Fixes...