Unify leaders and genders set up between mp::connect and mp::wait.

The relevant functions from mp::connect were moved to mp::ui to enable
them to use by mp::wait as well. This is not the most elegant solution,
but in the future mp::connect and mp::wait should be merged into one,
and those functions could be moved back to where they were.

leader_list.?pp has been removed since it is no longer used.