i've just added to stage/tools a little auto-placement utility, called
'autoplace'. it will randomly place your robots in free space (i.e., not
overlapping with anything else) within a rectangle that you specify. your
robots must have position and truth devices. it gets/sets pose info via the
truth device and checks for collisions via the position device's stall bit.
also, i fixed worldfile.cc so that world files can be saved without Stage
crashing (which makes autoplace much more useful).