starting combat stuff
completely untested, incomplete NPC code

this code just starts the NPC features to come, and it's untested. but
it builds
added basic respawn/NPCs

developed ticks, cached areas because calling GetAll<T> in a timer
seemed to be buggy, then realized timer just needed to be stopped while
in loop so new threads don't spawn 50ms at a time later.
more repop work, added clean shutdown

added basic logging
mobs randomly talk/walk

added look <npc>
fixed makeexit to set IsOpen=true when exit isn't a door
added corpse decay interval and mob walk interval to server (instead of
MobTemplate/PlayerItem) to see if i end up changing them a lot
started shopkeepers

added list/buy commands. buy works, but player item (even after save)
doesn't get saved on shutdown
fixed stupid buy item bug

"l" command no longer attempts to "list" but rather runs "look" command
added sell command

PlayerItem wasn't being cloned correctly, so added a deep copy and
tested.
fixed look at npc command