cl_type_of: give better results for (type-of <complex>)

Instead of simply returning complex we return:

  (complex real)

when code is built without complex float support, and otherwise

  (complex rational)
  (complex single-float)
  (complex double-float)
  (complex long-float)

New functions:
- ecl_to_csfloat
- ecl_to_cdfloat
- ecl_to_clfloat