Point tests pass

Moved over to a list based self.pheremones. Seems to have tidied code up
a lot.

Point tests pass, but need to make tests non-fragile and dependent on
self.decay being equal to 10.
Tidied up

Crossed some things off my TODO list.

Put spaces following my internal style guide and added placeholder doc
strings.
TODO Tidied

Todo Tidied and added simulation TODO