Phasing out get/set for properties. Did Cell.

I just learned about properties yesterday, and I want to use them.
Therefore, I'm phasing out all my simple get/set functions in favor of
direct access/properties where appropriate.

Also changed the __eq__ function of Cell to be more resilient.
Changed LevelInfo to direct access, no properties.

Properties unneeded.

Also changed __eq__.
Converted Level. Changed LevelInfo data members.

Python's lack of strict typing means that if you name two functions the
same thing, you're going to have slightly more difficulty hunting down the
usages of whichever one you want to change. It's...a bit vexing.
Converted LevelController.
Converted Destructible.
Difficulties with changing Entity. Restore point.

This is a convenient restore point. I have changed Entity._priority to
Entity.PRIORITY at this point. I have also fixed the issue with renaming
Entity._entity_name to Entity.entity_name, and done the renaming.
Converted Entity. Removed __eq__ for subclasses.

Finished converting Entity.

The __eq__ functions defined in subclasses were inconsistent and finnicky,
so I just removed them all. They will use Entity's standard:

return sorted(self.__dict__) == sorted(other.__dict__)
Converted Entity, removed child __eq__ functions.

All children of Entity will now use Entity's __eq__ function, defined as:
return sorted(self.__dict__) == sorted(other.__dict__)
Merge branch 'entity'
Checked out file from entity.

I have not yet gotten down how to resolve conflicts properly; the strategy
I used didn't do what I thought it would do. Therefore, I'm having to
manually grab the file. Sucks, eh? Need more practice!
Working on converting Actor; leaving library.

Also made Actor.detect_entities() private, and called at the very
beginning of turn_begin().