lib/macports/S: remove unused $_TOPT option

There are two cases (1) download only (aka patch) (2) download/install.
In the 2nd case, we do not need $_TOPT option, which should be empty
lib/00_core: Add :pkgng (FreeBSD) support
lib/00_core: clear _TOPT if :pacman is unknown
README: add :pkgng (FreeBSD) support
compile.sh: add :pkgng support
lib/pkgng: FreeBSD support, thanks to Konrad Borowski. Close #25