Making a connection between ensembles of different dimensions should give an error if you don't specify the transform (or pre/post indexes)

[tcstewar]

Right now if you do this:

net.make('A', 100, 3)
net.make('B', 100, 5)
net.connect('A', 'B')

the system default to this transform matrix:

[[1.0 0.0 0.0]
 [0.0 1.0 0.0]
 [0.0 0.0 1.0]
 [1.0 0.0 0.0]
 [0.0 1.0 0.0]]

This is horribly wrong and has led to confusing bugs.

My suggestion is that this should give an error, forcing you to specify either transform= or some combination of pre_index and post_index.

Another option might be to use the following as the default matrix in this case, but I think giving an error is the clearer option

[[1.0 0.0 0.0]
 [0.0 1.0 0.0]
 [0.0 0.0 1.0]
 [0.0 0.0 0.0]
 [0.0 0.0 0.0]]