openspecfun not building with Intel fort due to use of COMPLEX instead o...

I noted that the main Julia page recommends when using MKL that the Intel compilers should be used, at the moment openspecfun does not build with ifort. This is due to the use of COMPLEX to create a complex, instead of the standard CMPLX. Cleaned up code to use Double Precision Complex value into ZABS. 

It may be better to just use intrinsic ABS instead of the ZABS that is in the library.