Intuitionize nsuceq0 in iset.mm
Intuitionize nsuceq0 in iset.mm

Rename to nsuceq0g and just keep the A e. _V case. That will
suffice for peano3 and it isn't clear how to replace the
case elimination in the original nsuceq0 proof.

metamath/set.mm,metamath/set.mm,metamath/set.mm