Suggested fixes fixed

Fixed the function pointers (i've never used them before so I'll take your word on that)  and changed to unsigned int - I'll make it so if the iterator is moved out of range it MUST be reset by a SetTo or operator =.or it will only return NULL. I also added SetToFirst() and SetToLast(). I had it signed for the 0-1 condition, but this way is more consistent so better I think.

I also removed Remove(), lets just use Delete() which will need to inform each Connection that the PointMass is deleted (a function will be needed there).