Now train_net and test_net are constructed separately according to the two definition files. As is pointed out in #57, the definition files can be consolidated so that a single definition file creates both the train_net and test_net.

The consolidation can happen in memory level, namely use the same net for both train and test. The layer forward backward function can behave differently at running time according to the Phase parameter.

This will save memory needed by test_net, and also save time by avoiding memory copy from the train_net to the test_net.