upstream 0.3 (reverting all changes from this fork)
re-apply ba48d (python: distinct input/output vocabs; optionally skip one hidden layer)
expose premultiplication
cleanup Makefile
re-apply 31412f (osx compile)
re-apply 233de0 (Eigen library assumed to be in 3rdparty directory)
re-apply cfc957 (expose vocabulary map to Moses)
re-apply 64120 (support for networks with single hidden layer)