Merge pull request #1 from CookieH/master

Update Forked repo
Implemented A* agenda and changed implementation so that action state
pairs are now wrapped in a class called nodes to allow us to make sure
that they are comparable.

Need to restore Depth First search agenda.
Implemented A Star search through use of the heuristic interface.
Implemented Grid navigation. Will explain later!
Wrote method to translate output from GridPuzzle to be put onto the
robot. 

TODO -> Implementation of A* needs improving slightly in terms of
Heuristic.

Demo's Need setting up and maybe neaten it up so fewer objects have to
be created when swapping between agendas and puzzles
Merge pull request #3 from DaveM214/master

Merging Grid Puzzle