Towing/tugs#410

Ive seen multiple suggestions consisting on tugs and i agree with them I would love to see tugs especially at big airports like when a plane either goes from maintenance to a gate or a gate to a parking stand if the plane has a long layover I think this would make realistic schedules possible

almost the same as #373

Note that there are currently five topics (#373,#425, #428, #410 and #411) with (almost) the same request. Not sure if they can be merged ?