Added:
 - Nondeterministic Z-Automaton [1]
 - ArcFactored Deterministic Z-Automaton [1]
 - ArcFactored Nondeterministic Z-Automaton [1]

[1] Johanna Björklund, Frank Drewes, Giorgio Satta: Z-Automata for
Compact and Direct Representation of Unranked Tree Languages
https://doi.org/10.1007/978-3-030-23679-3_7



Co-authored-by: Tomáš Pecka <tomas.pecka@fit.cvut.cz>

avoid c-arrays

getRank used to return a class that was supposed to be compatible with
unsigned (and size_t) however now it is unsigned by itself

the field has its default value specified, no need for the initializer

... because most developers were copy-pasting the preambule anyway and
did not pay any attention to change it.

Also, I think that git does better job in managing that.

protected field break encapsulation

primitive types don't need std::move