In the context the order of iterators is that the returned value is
always positive

ints unnecessarily reduce range of values for indexes

remove not needed cast

Map keys are exactly corresponding to vector indexes in the algorithm.

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

... 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.

The case (b*+a)* was only optimized to (b+a)* by lemma V4.

Algorithm automaton::transform::AutomatonIteration resulted in wrong
output when the input automaton had a transition from the initial state to a
final state.
If such transitions exists, we must also add a transition from the new
initial state to the old initial state in the new automata.

Added a test case for this particular case.

Closes #211

There were two instances of the AutomatonIteration::iteration method,
one for working with DFAs, one for NFAs. However, both shared the same
code.
Let's merge those methods.