Fixed slowdown.

Was being caused by a SenseSeismic with range of 99 in the robot
adversary.
New class Command for entity manipulation.

New class Command created. Intention is to allow entities to manipulate
the level and other entities, without having to directly manipulate the
entities/cells, as well as keep a log of actions.

Keeping a log was the original intention, but I figured as long as we're
making logging objects, we may as well make it into a Command.
Moved eid out of LoaderEntityIndex and into Level.

It was a bit silly that LoaderEntityIndex, which was supposed to simply
load the entities, tracked the current entity index. Moved into the Level
class instead.
Just tidying up the Level class.

Replaced calls to get_cell_at() with direct access where appropriate.
Looking to remove it fully.
Beginning to implement Commands.

testCommand.py is testing class.

Most of the work won't actually be in the commands themselves, it'll be
retooling the existing code to use them.
Changed Commands to Records.

On reflection, there's not much advantage to moving the logic out of the
behaviors/tools/whatevers into the Command. It's set up so that the
creator of the Command has everything it needs to do whatever it is it
wants to do, and I'm not planning to support undo options. So what
advantage does using the Command pattern give?

Since I can't identify any, I'm changing it to a more simple logging
system.