Updated demo map and added small test map

Signed-off-by: Hayk Martirosyan <hayk.mart@gmail.com>
Add interactive mode

When run with the -i flag, sets interactive=True in Simulation. When
used, waits for the user to hit enter between each frame. Great for
debugging.

Signed-off-by: Hayk Martirosyan <hayk.mart@gmail.com>
Add comments to Simulation class

Signed-off-by: Hayk Martirosyan <hayk.mart@gmail.com>
Add move history to structure and render it

So when the simulation plays, the structure is shown being built in the
right spot (by the dropoff point). However, generation of the correct
structure position is not implemented yet.

Signed-off-by: Hayk Martirosyan <hayk.mart@gmail.com>
Bugfix: Stuck when bot starts on goal

Previously, if a bot was assigned a goal on its current position, it
would go to an at_home state and mark its goal as None. Then, the
at_goal function would return False, making it look like it is not done
yet. Now, planning module checks if at_goal or has_goal.

Signed-off-by: Hayk Martirosyan <hayk.mart@gmail.com>
Added objects for attach_rod_x, attach_rod_y

Probably need a more generic way to generate objects based on station
types. How does this get color coded?

Signed-off-by: Hayk Martirosyan <hayk.mart@gmail.com>