Finish off docs for MS_info
Finish off docs for MS_info

Also:
* Fix minor bug in input arguemnts error checking
* Add 'rot' and 'vel' modes
* Allow output to be put in a string (not printed out).

alanfbaird/MSAT,pusher96/MSAT,jwookey/MSAT,jwookey/MSAT,alanfbaird/MSAT,alanfbaird/MSAT,jwookey/MSAT,pusher96/MSAT,pusher96/MSAT