Templatize a lot of functions in backend_agg
Remove more Python references.
Reformatting
Improve exception handling
Remove more Python references
Tackled _path module
Reinstate some docs
DeCXX _png extension
Move convert_array to numpy namespace
DeCXX _gtkagg
Various fixups
More minor fixes
Add note
Let Python handle the instance variables for us.
More progress on fixing tests.
Fix more tests