Implement enemy status immunities

Surprisingly, this hadn't yet been implemented, despite the list of
immunities being part of the enemy definitions.  I blame lazishna.
Allow coloration for healing indicators

Just like damage, healing/evasion indicators can now be colored as well.
Work on Scott Temple, add Justin as battler

Justin's main role is that of a healer.  However, there's a twist there:
his secondary role is to remove status buffs via Purify.  Believe me,
that'll come in real handy once Temple starts casting Rejuvenate all
over the place!