Minimap Events

[trepan]

Starting converting my old MinimapDamages to use UnitDamaged():

http://trepan.bzflag.bz/spring/minimap_events.lua

It's a work in progress, but worth taking a look at. The scales and
clamps need some tweaking, and I may jazz it up a bit with some
extra event types, and custom (animated) event icons.