EventManager: prevent eventspam just after loading a save.
eventful: no longer possible to disable an event type, event frequency is the minimum request frequency (most frequent), added array of event handler function pointers to simplify code
Several EventManager fixes and improvements.

- handle loading and unloading of saves better
  - made sure it never triggers bogus events on loading a save
    - plugins should now handle loading themselves with onStateChange
  - special case to make Buildings module keep track of all buildings correctly on load
- fixed syndrome detection
  - was broken because of the switch from ticks-since-the-dawn-of-time to world->frame_counter
  - added lastSyndromeTime global
- fixed possible off by one error when looking for new created items
- got rid of the unread lastTick global
- const'ed the function pointer array of eventManagers
EventManager: fixed the TICK event, and a few tweaks.

- redo tick event management to work with world->frame_counter
 - the freq of a TICK EventHandler is now ignored
 - unregistering for an individual TICK event is still broken
  - you would have to know the modified freq to even begin removing it
  - it is only removed from handleres[TICK], not from tickQueue
- redo unregisterAll to be more efficient
- use the map loaded/unloaded events instead of world loaded/unloaded for initializing/clearing event monitoring data
- get rid of silly unsigned variables
EventManager: TICK events should unregister correctly when requested and after they fire, other tweaks.

- fixed unregister to allow unregistering individual TICK events
 - make registerTick return the resulting freq you have to put back in to the handler in order for it to be unregisterable
- when TICK events fire, they now automatically remove themselves from handlers[TICK], as they should
- make sure manageTickEvent fires once per tick
EventManager: be smarter about removing things while iterating.