Fix drawing of markers with no stroke
Improve marker_edge test for this case
Remove PyCXX from _tri module
Completely remove PyCXX
Remove duplicate import_array() call
Fix invalid symbol if numpy 1.6
Merge pull request #3723 from ianthomas23/final_decxx

MNT : Complete removal of PyCXX
Merge pull request #3725 from ianthomas23/3712_numpy_1.6_symbol

MNT : Fix invalid symbol if numpy 1.6
Merge pull request #3724 from ianthomas23/duplicate_import_array

MNT : Remove duplicate import_array() call
Merge pull request #3687 from mdboom/marker-edge-width

BUG : Errorbar markers not drawn in png output