* General cleanup.
* Add ldexp, use it in pslq codes.
* Add ceil, floor.
* Sun CC compiler: should we add -erroff=wvarhidemem flag to disable 
  variable shadow warning?  Or should we eliminate variable shadowing?
* Make it more consistent with standard math library.
* Should we use <complex> ?
* erfc now uses C++, but rather ugly, clean it.
* More efficient mp_real + double ?
* More consistent dispatch of high/low precision routines.
* Use static_cast instead of C-style cast.
* Check for int32_t, and use it instead of generic integer.
* Better handling of error conditions.
* Sign function?  Maybe use copysign.
* Documentation.
* Thread safety.
