Added 'Module:findModulesByTypename' function.

This is a super helpful function...  I use it all the time in my code in various places.  It's a Module function that returns all the nodes of a give typename ("nn.SpatialConvolution", etc) in a flattened table AND it returns the container modules of those nodes in another table.  It makes poking around models and modifying them a little easier.

See description in the docs for an example.