Allow can_carry_multiple to be set for non-pylon equipment

PS.equipmentStatus(eqKey,true) now returns a dictionary of statuses,
to allow damaged state checks on multiple items. ...(...,false) will
return EQUIPMENT_OK if at least one is still working.

Can probably use this to take out all the messy hard-coding of passenger
berths, but that can be done later.
Merge branch 'master' of github.com:OoliteProject/oolite