added isnan function to Numeric-flavored numerix
Added _isnan extension module to test for nan with Numeric
rm self._pswriter.write lookups from draw_markers
fixed a bug in draw_markers and draw_lines
fixed an array as truth value bug in ps with numpy
changed suggested ghostscript version from 8.16 to 7.07
made new API default in PS
fixed for numpy array scalars (thanks Eric!)
Fixed image.aspect in matplotlib.template.
Aspect handling modified for imshow.
