feat: CompactMealy clone constructor

[tiferrei]

Hi there,

I recently needed this functionality, so thought I'd make a PR to upstream the change. Please let me know if there's a better / preferred way of doing this.

Thanks!

[mtf90]

Hi @tiferrei, looks like a nice little convenience function. However, do you need the CompactMealy(Alphabet<I> alphabet, CompactMealy<I, O> other) constructor to be public? In the corresponding CompactDFA case this constructor is protected because it can potentially cause some issues if the alphabets don't match (it is only used by the translate method).

[tiferrei]

Ah good catch! I do not indeed, I only copied it (badly), I will fix that.