Changed comedi_set_calibration() to comedi_apply_calibration(), and

Changed comedi_set_calibration() to comedi_apply_calibration(), and
made it much faster, it takes <100msec to run instead of >1sec.
It requires linking to libperl now (hope that's
okay).  Renamed DEBUG() and _() in libinternal.h to COMEDILIB_DEBUG()
and GETTEXT() in order to avoid conflicts with perl headers.