Add references + description for each domain

[[e-mail]]

add a reference for each domain or, if there is no existing work, have an elaborate description. A brief description should be there in any case. This should be done by the respective author of the Domain if possible.

Domains not covered in other tasks:

• IntruderMonitoring - done
• MountainCar
• MultiTrack
• Pacman - done
• Pinball - done

[Will Dabney]

I've added a reference to Pinball and expanded the description of IntruderMonitoring. The multitrack description seems pretty reasonable for now, but could use a reference.

Pacman sort of references BerkeleyX/CS188.1x, but could definitely use a more thorough description and reference that can be followed up on.

[[e-mail]]

refined docstrings of PST, Pacman and Pinball

addresses issue #17

→ <<cset ac71101b14ae>>

[Robert Klein]

Removed multitrack domain

[Robert Klein]

fixes #17

→ <<cset 9577f2e1c58b>>