AngledMarginPen? calculates the left and right side-bearings of a glyph, relative to slanted margins. The angle is taken from font.info.italicAngle. Curves are approximated. This also contains 5 convenience functions to set and get individual margins and to center the glyph.
The approximation can be improved upon, perhaps taking the size of the bezier into account and so on. Also the italic offset, as it was used in RoboFog? is missing, and could perhaps be taken into account.
