[Freeciv-Dev] (PR#6342) gtk2.0 / 1.14.1beta: allow more than 2 units to show in sidebar

["Guest" <rt-guest@xxxxxxxxxxxxxx>]

The sidebar (the pane that shows you population, turn done, and units)
currently shows the selected unit and at most two units in its location,
with an arrow if there are more.  Three requests, by priority and
probably by implementation ease:
(1) always show how many units are there
(2) show as many as fit in the pane -- if I resize it to be larger it
    should show more units
(3) clicking on the arrow should scroll through the units