-- Began integrating spatial-events with the world handler, with
the end goal of letting cells load and tick their own units
independently (detachable child processes). Spatial-events allows
multiple event handlers with the same name, getting triggered depending
on where an event occurs in 3D space; it increases performance
with an octree behind the scenes.

Signed off by Mark Farrell <markfarr2011@gmail.com>
-- Began integrating Zones into the worldHandler. Also simplified
some repeat code in worldHandler.

Signed off by Mark Farrell <markfarr2011@gmail.com>
-- Abstracted the find functions in worldHandler.

Signed off by Mark Farrell <markfarr2011@gmail.com>
-- Removed references to worldHandler.world in ConsoleHandler and
SocketHandler.

Signed off by Mark Farrell <markfarr2011@gmail.com>
-- Removed references to worldHandler in ./Game/

Signed off by Mark Farrell<markfarr2011@gmail.com>
-- Removed references to worldHandler.world in ./Game/Special

Signed off by Mark Farrell <markfarr2011@gmail.com>
-- Removed remaining references to worldHandler.world in
Game/Fighter.js, Game/Player.js and Game/Unit.js

Signed off by Mark Farrell <markfarr2011@gmail.com>
-- Made every method of WorldHandler asynchronous (return promises)
-- Added listens() to the prototype of SpatialEventEmitter
(spatial-events), to reject a promise whenever there is no listener for
an event that is emitted in zones. In the future, should add these
changes to the spatial-events package, also updating Tree instead of
having nodeListens as an inline function.
-- State checking is no longer necessary in world ticking, because
ticking no longer begins until the world has loaded its units and been
awaken.

Signed off by Mark Farrell <markfarr2011@gmail.com>
-- Added asynchronous control flow everywhere references
to WorldHandler's member methods were made.

Signed off by Mark Farrell <markfarr2011@gmail.com>
-- Began writing tests with TAP output for new the WorldHandler.

Signed of by Mark Farrell<markfarr2011@gmail.com>
-- Fixed issues preventing players from receiving snapshots
with then new WorldHandler.

Signed off by Mark Farrell <markfarr2011@gmail.com>
-- Fixed issues with loot and respawning caused by the new updates to
the WorldHandler.
-- Began adding documentation to the zones modules.

Signed off by Mark Farrell <markfarr2011@gmail.com>
-- Fixed issues with the in-game editor caused by updates to the world
handler.
-- Simplified in-game editor logic; created a single 'edit' event that a cell
listens for.
-- Created worldhandler directory under Engine, with the intent of
making index.js be the default module when requiring 'worldhandler' and
having 'zones.js' and 'snapshots.js' as support modules.

Signed off by Mark Farrell <markfarr2011@gmail.com>
-- Cells now listen for events at points in cell coordinates. This
prevents multiple listeners from being called when an event is emitted
on the border between cells (since boxes in world coordinates were used
previously).

Signed off by Mark Farrell <markfarr2011@gmail.com>
-- Fixed an issue with triggers caused by updates to the world handler.

Signed off by Mark Farrell<markfarr2011@gmail.com>
-- Fixed mistakes made in ./Game/Special/trigger.js and
Engine/worldhandler/index.js

Signed off by Mark Farrell <markfarr2011@gmail.com>
-- Fixed issue 411, where units were not removed clientside when the
player changed zones.

Signed off by Mark Farrell <markfarr2011@gmail.com>
-- Cells now start ticking themselves when activated, and stop ticking
themselves when fully deactivated (no players). More often than not, players only
occupy a relatively few cells at a time. It is rather wasteful to iterate
over all units in all cells in all zones each tick, finding in most cases that nothing
should be done when unit.active is false. These changes make it so that
redundant checks to do not occur. Server start up time appears faster,
but performance gains have not been quantitatively measured.

Signed off by Mark Farrell <markfarr2011@gmail.com>
-- Added the Ticker service to control how often ticks are
scheduled, to prevent node from hanging.

Signed off by Mark Farrell <markfarr2011@gmail.com>
-- Fixed the issue where players would don't receive an appearance update
when they die and lose their items.
-- Fixed an update to Unit that caused enemy target-finding to break.

Signed off by Mark Farrell <markfarr2011@gmail.com>