From Emergent

New Connection Design in 4.0

The new connection is just a plain non-virtual non-ref-counted object, which is fully managed by a RecvCons owning object. This saves a lot on memory allocation and efficiency of traversing the objects.

Key changes:

• Con_Group does not exist, and can usually be replaced with RecvCons (rarely SendCons -- you'll get a compiler err in any case.
• recv.gp.size -> recv.size; send.gp.size -> send.size
• size -> cons.size within RecvCons or SendCons
• FOR_ITR_GP ->

    for(int g=0; g < un->recv.size; g++) {
      RecvCons* recv_gp = un->recv.FastEl(g);
      ...
    }

• 'if(u->bias) bias->' -> 'if(u->bias.cons.size) u->bias.Cn(0)->' (bias is now a RecvCons, can also pass its addr to relevant conspec functions!)