Esko Toivonen

### Bug summary Because the pixel x coordinates of scanline cells are casted from 32-bit integers to 16-bit ones in Agg ([this line](https://github.com/matplotlib/matplotlib/blob/3b79f63980c767fabc59ec5ba267818d8b4b5671/extern/agg24-svn/include/agg_scanline_p.h#L96)), some polygons that are outside the drawing...