* ginac/registrar.h: dtor is inlined now.

* ginac/registrar.h: dtor is inlined now.
* ginac/basic.h, ginac/ex.h: removed INLINE_FOO_CONSTRUCTORS and hand-inlined
  stuff instead, since the macros turned out to get in the way while
  fine-tuning the inlining.
* ginac/utils.h: if 'long long' works, use that one for computing the hash
  value instead of floating point tricks.  2 Reasons: on Intel the assembler
  is terrible and slow otherwise, 'long long' will appear in C++ anyways when
  they adapt to the C99 standard.
* Several other small performance tweaks.
* ginac/constant.cpp: (constant::calchash()) implement, caring for serial.
* ginac/function.pl (function::calchash()): implement, caring for serial.
* ginac/expairseq.cpp: honor coeff's hash value.
* ginac/pseries.cpp: (pseries::power_const()) fix problems with zero pseries.
* Added several pounds of in-source documentation in doxygen style.