Ngesh

- Added exact number of leaves as stop criterion

- Small bugfixes, related to JOSS publication

- Release for JOSS publication

- Code improvements preparing for release and submission
- Included new faster generation method contributed by NicolaDM

- Fixed bug with character generation during simulation of horizontal
gene transfer
- Fixed bug in upper boundary number of syllables for label generation

- General improvements for submission
- Extended function documentation and in-code comments
- Documentation at ReadTheDocs.io
- Complete output (whenever possible) for all output formats
- Complete command-line access to all parameters, such as for hard
politomies
- Automatic code review, more tests
- Removed dependency on the `abzu` library