Animation for WXAgg

I have just submitted a patch against CVS to sourceforge which adds support for animation to the WXAgg backend. It also includes an optional C++ extension module intended to speed up the conversion from an Agg image buffer to a wxPython bitmap or image.

I would really appreciate any feedback you all have to offer, especially on the follow points. Thanks in advance!

  1. How does the _wxagg.cpp module look? I've never dealt with Agg before, nor have I make a
     Python extension using CXX.

  2. Are the changes to and correct and/or sensible? I've tried to keep
     things tidy while dealing with being unable to find the `wx-config' program. Since animation
     works without the presence of the WXAgg accelerator, I don't think it makes sense to abort the
     build process when BUILD_WXAGG is set to "auto".

  3. What kind of performance increase are you seeing, for both blit-based animation and regular
     drawing? I'm not expecting that you see much of an improvement, due to limitations in the
     way wxPython deals with raster image data, but it would be useful to know.