2 more examples working..

Fixed with update to nml2 comp type defs & examples here:
https://github.com/NeuroML/NeuroML2/commit/31322778bceb5f45d48ae7f26c883227dc3d8756
Issues down to change of g from DerviedVariable to StsteVariable in
expOneSynapse & mismatch in passiveChan name in Ex6&7