Draft: Resolve "Add possessive quantifiers"
Closes #3
I need to think of a better way to integrate this into the VM. Being able to reset o an earlier string index is problematic, not only for complexity guarantees but also because it can easily create duplicate states (and hence results).
Also there is a failing test.
Particularly difficult cases I found:
Start = match "[^a]{0,1}+" "abc"
Start = match "((aa|a)a)*+" "aa"