Added function that gets all words of an automaton

[codecov[bot]]

Codecov Report

Attention: 1 lines in your changes are missing coverage. Please review.

Comparison is base (efadb56) 72.05% compared to head (3707ce7) 72.20%. Report is 8 commits behind head on devel.

:exclamation: Current head 3707ce7 differs from pull request most recent head 77da58f. Consider uploading reports for the commit 77da58f to get more accurate results

Files	Patch %	Lines
src/nfa/operations.cc	95.65%	0 Missing and 1 partial :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## devel #375 +/- ## ========================================== + Coverage 72.05% 72.20% +0.14% ========================================== Files 30 30 Lines 3686 3709 +23 Branches 839 846 +7 ========================================== + Hits 2656 2678 +22 Misses 735 735 - Partials 295 296 +1 ```

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[jurajsic]

I am ok with merging