Expose `is_mentioned` in `message` dict which contains
boolean value about our account is mentioned in the message
content or not.
This is already available via `flags`, but it seems worth making this
data point more explicit, given its importance in writing bots.
Fixes#2667.
A few functions had arguments removed without having their type
annotations updated accordingly. As a result mypy version 0.4.6
thinks that the first type in the annotation is supposed to be
the type of `self`, a new mypy feature which we are not intending
to use here.
Juan Verhook
Rafid Aslam
Reid Barton
bulat22101
AZtheAsian
Tim Abbott