add rent only / return only stands

[nekromoff]

when stands needs to be removed / replaced, set special tag (serviceTag?) so it will only allow renting, but not returns.

please, discuss, then reassign.

[mmmaly]

Either use a different bit of service tag, e.g.: 1st bit (1) - don't show in map/FREE command 2nd bit (2) - don't allow rentals from this stand 3rd bit (4) - don't allow returns to this stand.

Or create a different column (serviceTag -> dontShow, dontAllowRentals) and create maxNumberBikes. After reaching maxNumberBikes, no more returns would be possible.