1.0.29.44: Complex float improvements

1.0.29.44: Complex float improvements

* On all platforms:
 - Slightly more stable complex-complex float (double and single)
   division;
 - New transform for real-complex division;
 - complex-real and real-complex float addition and subtraction
   behave as though the real was first upgraded to a complex, thus
   losing the sign of any imaginary zero.

* On x86-64
 - Complexes floats are represented packed in a single SSE register;
 - VOPs for all four arithmetic operations, complex-complex, but also
   complex-real and real-complex, except for complex-complex and
   real-complex division;
 - VOPs for =, negate and conjugate of complexes (complex-real and
   complex-complex);
 - VOPs for EQL of floats (real and complexes).
 - Full register moves for float values in SSE registers should also
   speed scalar operations up.