TODO

• Add an entry in doc/news/.
• Add a test for this change.
• Add new .py files to the documentation in doc/geometry or doc/graphical.

Expose through ThurstonVeech or cylinder decomposition

• Expose horizontal_twist() and vertical_twist().
• Implement regions().
• Implement veech_group() and random_element() there.

Implement Region:

• Implement width() and height().
• Implement intersection() to intersect a region and a line to obtain a segment.
• Implement horizontal_cylinder() and vertical_cylinder().

Implement Cylinder:

• Implement circumference().
• Implement multiplicity().