use C++ std::isnan() instead of our own
add files I forgot to add in last commit
some minor cleanups in transform limits stuff
revert r3512, which broke on Mac
finished numpification of extension code and axes.py
Removed our own MPL_isnan.h in favor of numpy's implementation
reverted some broken test code
fixed a distance bug in arrow
Fix segfault in Tk backend.
Add TTF subsetting to backend_pdf.py.
