Added optimization in Elemwise C code generation.

Elemwise now works on simple case generating only one C file. I'll add the dtype declarations for differents dtypes input in a later commit.
checkNDim and checkType are always empty string.
I think you should add the checkType for set(inames).remove(inames[0]) if the config var tell so. Then you also need to check for Ndim each var in set(inames)