Pipe

[opeltre]

Add module composition

Given g : X -> Y and h : Y -> Z, the module composition f : X -> Z can be obtained by either:

f = Pipe(g, h) 
f = h @ g

If h.loss(out, *tgts) is defined then the resulting composition f will also have the methods f.loss(out, *tgts) and f.loss_on(in, *tgt) defined.

=> Helps #10