Changes how companions speak

Companions now have a periodicMessage(Actor*) function that is called
when the engine says its time for them to speak. If you notice, the
function contains a large switch-case, which switches on the Attitude
field of the particular companion. These attitudes can be found in
Ai.hpp, and will be randomly determined as of tomorrow.

Feel free to add more speech bubbles for whatever attitude you prefer.

One last thing: companions may also feature some variety in how
frequently they speak, the period between which will be determined when
they are first created.

Capybara? More like Crappybara, amirite?