Opt-in Combat Time

Records the last time a player engaged in opt-in combat, which includes
soldier shields, guild wars, and outlaws/murderers.

This will be very useful for future mechanics. This will give us the
capability to differentiate between opt-in combat that players chose to
be part of versus opt-out combat involving PKs attacking unwilling
victims, *and* it will give us a metric for whether a player is actually
currently in such combat.

This would, for example, allow us to change penalties or ghost times
for opt-in pvpers actually engaged in combat, but without changing
how innocents experience the game.