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.
I'll start a 3th time. checkNDim and checkType is empty.

I think you should call c_check(...,checkType=False,) before the check for dtype.

Then, after a succesful comparison with inames[0] dtype, you need to add the dtype check for set(inames).remove(inames[0])