Transplant an old score layer's parameters, with k < k' classes, into a new
    score layer with k classes s.t. the first k' are the old classes.

def expand_score(new_net, new_layer, net, layer):
    """
    Transplant an old score layer's parameters, with k < k' classes, into a new
    score layer with k classes s.t. the first k' are the old classes.
    """
    old_cl = net.params[layer][0].num
    new_net.params[new_layer][0].data[:old_cl][...] = net.params[layer][0].data
    new_net.params[new_layer][1].data[0,0,0,:old_cl][...] = net.params[layer][1].data