Added pry to rspec helper
Patch for nested backrefereces

I'm pretty sure this is still not a complete solution to the problem! Although, it does
make the existing tests all pass.
TODO: Add more tests to highlight the outstanding issue (if it exists)
Fixed OrGroup, so all related spec pass

The logic was wrong, following an early refactor I made.
I think this should work for all cases, but should come up with some
more tests to prove it.
Char groups work with backslash chars, like \w

e.g. /[\w]/.examples

All tests now pass!!!!
Now I need to add more tests, to prove it DOESN'T all work :D
Made each test only call Regexp#examples ONCE

This makes debugging easer, if you add breakpoints
Added more char group tests

Also fixed a simple bug that was found as a result of these tests!