fix issue#2 - 0.23 Makefile.PL changes lost deps
name even core dependencies of 5.8 to support ...

older Perls, too
hppa support & improved 5.6

* adjust $LIBEXT/$EXEEXT initialization to support HP-UX/HPPA
* use an own looks_like_number when no Scalar::Utils is available
Note changes for 0.24