Removes commit method from Actor.

Unused method. Object is mutable from any updater, so conditions will in
fact stack. This is fine because updaters should not be doing too much
comparing and events that affect the player will be performed in a
different area.

This means frames are not transactions. Maybe it will become more
reasonable, but the amount of complexity added would be too much. So,
the order of actions might matter, but that order is determined by the
game designer.

It probably would be either immediately noticable in the case that the
conditions are common, or very obscure in which the problem will be
rather curious but not horrible. Although this means bugs triggered by
ordering will be hard to reproduce.
Adds Engine::Object to handle pathing and object loading.

This Engine will coordinate with the individual Registry::* classes and
will load various objects in the system. This Engine understands the
path and file system hierarchy given to it and can easily figure out
where objects should be loaded from.

The Object Engine will easily be able to read generic object
descriptions and will then pass on relevant parts of larger JSON
descriptions to individual Registry constructors. This should allow
better flexibility for project descriptions.

Another bonus to add to the Object Engine is the ability to compress
game files. This Engine will be responsible for decompressing.