Allow adding multiple parsers to TypedConfigParser in a single method call

[Guillermo Gonzalez]

It would be nice to have a TypedConfigParser.add_parsers method to simplify adding multiple parsers.
I think it could be something like:

def add_parsers(self, parsers):
    for name, parser in parsers:
        self.add_parser(name, parser)

If I can get some spare time I'll propose a branch with this.