mxit libpurple protocol

[Ethan Blanton]

Andrew Victor spake unto us the following wisdom:
> I have committed patches for all these issues to:
>    ssh://hg@hg.pidgin.im/private/talos-2016-04-14

Awesome, thanks Andrew!

> If somebody has time to review the changes, that would be much appreciated.

Volunteers wanted!  We also need to develop a fix for the
recently-reported certificate init vulnerability.  We should run it
past the reporters if possible.

Ethan