Add public: fromalias(), has_alias().

Update documentation for enumeration types.

Implement new op param type `EnumType`

Updated numpy as np #4218

Fix memory leak

Remove the old backend and all of its tentacles

It seems sphinx 1.5.1 is not available for Python 3.3.

Updated numpy as np #4218 

Use expm1 for elu

2.Updated numpy as np