Some improvements

Hello. I improved a little bit your class as i want to use it in my framework in CLI mode.

So, here is a list of changes:
1. String can be given to parseArgs (so, the type mixed - array or string)
2. Triming " and ' at beigning and ending of a value
3. Short values, opts and long values are returned in separated arrays
4. Values conitaining "\" are joined in to one (example: Jan\ Kowalski)