Various new features for the argument parsers.

The argument parsers now have the following features:
- Backslashes to make multi-word arguments (multiple\ words)
- The flag-parsing terminator from WorldEdit (two hyphens: —)
- An alternate method to make a value-optional flag have no value
(uppercase flag: -A)
- An escape function for quoted arguments (backslash before the quote)

I think I’m going to start committing to this more often.
No pun intended.