Construction from Layer specification objects.

[alexjc]

New syntax for specifying layers that makes it easier to pass-in (and document) parameters. This provides error checking by default, too.

Updates #3, #6, #12, #18.

[coveralls]

Coverage remained the same at 100.0% when pulling 99f9155 on params into c638eef on master.

[coveralls]

Coverage remained the same at 100.0% when pulling bea3bba on params into c638eef on master.

[alexjc]

I think this one is ready for review, @ssamot. Thanks :-)

[coveralls]

Coverage remained the same at 100.0% when pulling 28bbc16 on params into c638eef on master.

[ssamot]

I think this is overall great, but it could be the case that having just on Layer type might prove too confusing (it might make new users confused about having to define a softmax layer with kernel). On the other hand if you have each layer type in each class it might be too confusing as well, too many objects flying around. I think the proper level of abstraction is Layer, PoolingLayer and ConvolutionLayer - what do you think?

[alexjc]

I'm not sure about having a separate Pooling layer because it's implemented as part of the convolution in pylearn2 and therefore might be a bit fragile if we decouple it; we'd have to check that Pooling is only ever added after Convolution, and only once.

For the Convolution, that sounds reasonable... If we can support more convolution layer types at the same time, why not! I'll make a separate ticket though.

[coveralls]

Coverage remained the same at 100.0% when pulling fcc28a5 on params into c638eef on master.

[ssamot]

Agreed - rest looks great and can be pulled

[alexjc]

Created new ticket #20 for improving the convolution support.