Second conversion Remove epsilon FINISHED!!!

* Some functionality moved from RegExpToFA to class of Algorithm.
* Add to this conversion functionality of show correct solution and bact to user solution.
* Finished EpsilonCloserWidget and it autonomous - check correct epsilon closer automaticaly.
* Fully finished RemoveEpsilon and add also 2 examples.
* Send sichnal about FA changed also from class Arrow.
* Add assign operator to ComputationalRules - without this asighn wasnt always correct.
* Repair of "random" generate of nodes in scene - seed for generating nodes is set only once.
* When removing last rule with some symbol also remove this symbol in class FiniteAutomata.
* Finished notification about changing FA throw many classes.
* Cleaned and refactor MainWindow.
* Repaired bug when trying qsetToQstring(QSet<QString> set) with empty set in set_of_sets.cpp.