Add format_mission_results

This catches a subtle bug: !missions won't show how many fails on the
4th mission in a 7+ player game
get_loyalty_info: always show roles

It will soon be possible for Base games to have roles, and it does no
harm to use the same code here.
tell_loyalty_to: Always check specific role even in Base games

We will soon have Base games with roles and this will help.
Implement Reversers

Closes #24