Support mentions

[donaghhorgan]

It would be nice if the Message class had a mentions method that you could use to check whether a given message mentioned a given user, e.g. something along the lines of this:

message = Message.parse(...)
if message.mentions("+1234567890"):
    do_something()

I'd be happy to contribute a PR if you're open to it?

[tzabian]

@filipre the above PR adds mentions to the Message container. Also added raw_message which currently always returns None

[filipre]

Thank you again @tzabian . mentions will be available in the next release.

Right now, mentions contains a list of dict looking like this

{'name': '+49123456789', 'number': '+49123456789', 'uuid': 'asdfasdfasdf-asdfasdfasdf-asdf-asdfasd', 'start': 9, 'length': 1}

I may add the check from OP at some point later