In optimization, constraints are frequently plotted with a ticked line -- where
the ticks indicate that one side of the line is invalid. TickedStroke implements
a PathEffect to draw lines with a ticked style. The spacing, length, and angle
of ticks can be controlled.

PR Summary

PR Checklist

• Has Pytest style unit tests
• Code is Flake 8 compliant
• New features are documented, with examples if plot related
• Documentation is sphinx and numpydoc compliant
• Added an entry to doc/users/next_whats_new/ if major new feature (follow instructions in README.rst there)
• Documented in doc/api/api_changes.rst if API changed in a backward-incompatible way