Bench:
- from Andreas Enge 9 June 2009:
  Scripts and web page comparing timings with different systems,
  as done for mpfr at http://www.mpfr.org/mpfr-2.4.0/timings.html

Efficiency:
- from Andreas Enge 16 September 2008:
  Once mpc_sin_cos exists, improve mpc_tan to use it

New functions to implement:

  a) needed for C99 support:

     - from Andreas Enge and Philippe Théveny 9 April 2008
       work plan for completing functionality
       inverse trigonometric and hyperbolic functions (needed for C99 support)
       that is mpc_acos, mpc_asin, mpc_atan, mpc_acosh, mpc_asinh, mpc_atanh

  b) other functions

     - from Andreas Enge 16 September 2008:
       mpc_sin_cos (needs mpfr_sinh_cosh)
     - from Mickael Gastineau <gastineau@imcce.fr> 14 Apr 2008:
       mpc_fma: d=a*b+c
     - from Andreas Enge 9 April 2008:
       mpc_pow_ui
       Also add mpc_pow_z, _d, _ld, _si, _fr (K. Ghazi 17 Jun 2009)?
       What about the mpc_foo_pow functions?
     - from Andreas Enge and Philippe Théveny 17 July 2008
       agm (and complex logarithm with agm ?)
     - from Andreas Enge 25 June 2009:
       correctly rounded roots of unity zeta_n^i

New tests to add:
- from Andreas Enge and Philippe Théveny 9 April 2008
  correct handling of Nan and infinities in the case of
  intermediate overflows while the result may fit (we need special code)