Now camera is handled through a simple "camera" op for networks and
"red", "green", "blue", and "gray" node ops to link nodes to image
channels. Note: only one red, gree, blue, and gray node in a network is
supported - worth expanding?
Merged new camera handling
Removed network size variable (of doubtful utility and invalid if any
node group changes size). Also, modified nodes and weights load to
return 0 rather than fail if no object can be loaded. This lead to a
better file format in which there is no need to specify the number of
groups and matrices for a network!