Prepare for Unicode 13.0 (major version update)

[jamesohortle]

Cf.: http://unicode.org/versions/Unicode13.0.0/

The datafiles will have to change.

[jamesohortle]

As of 9a5fb41 the data update has been completed. However, we wish to refactor how the regexes are used before the v1.0.0 release as well.