Implement noodlification

[Adda0]

This PR implements function noodlify for noodlification of NFA.

As agreed upon, we implement a naive noodlification method creating all noodles: all permutations of epsilon transitions, one from each depth. In the following PR, we will improve the current implementation with a new algorithm, creating only actually possible noodles which have a path in the original automaton.

The code has been tested with some tests.

[martinhruska]

Why is noodlify.h needed? Could not be the function declared in nfa.hh?

[Adda0]

It could be, of course. However, when discussing this with @vhavlena, we decided that it would be better for noodlify to have its own header and source files for the following reasons:

• The function stands somewhat aside from the normal operations on NFA. We think it would make sense to include a separate header file if the user wants to work with these operations concerning noodlification.
• We expect to have multiple new functions working with noodlification and its variations implementation in the future. For that reason, we think it is better to have a separate header file to explicitly distinguish between normal NFA operations and the operation for noodlification and related functions.
• Furthemore, we have plans for a more efficient representation of noodles which will require some new structures implemented. noodlify.hh is a better place for these structures than the general nfa.hh

[tfiedor]

I'm OK with the PR except for two minor things:

1. Add to comments what the noodlification and noodle is.
2. Fix the possible accidental quadratic complexity.

[Adda0]

I have addressed the mentioned issues. Furthemore, I have split the noodlify() into smaller functions in hopes of reusing the smaller functions in the future for aforementioned additional operations for noodlification.