Add Overload :: Parser.ParseArguments(string args)

Is there any interest in allowing the `ParseArguments` method to accept a single scalar argument?

My use case is a console app that, if no arguments are supplied, goes into REPL mode.

I'd like to use this package to handle text the user puts into the REPL but it comes as a single `string`, not a `string[]`. I can roll my own or look for another package but figured I'd ask.

If there's interest, I'll work on PR.