Moving a bomber

When you type g to move a unit, its current movement balance is no
longer displayed.  This makes it easier to move a bomber by mistake,
when it is in a city but does not have its full movement allowance,
and run out of fuel.

It would be a good idea to ask for confirmation before moving a bomber
in such a way that it will run out of fuel before returning.

It would be quite convenient to have a command to move a bomber back
to the last city it was in, or perhaps, to the nearest friendly city.