INSTALL: update with FreeBSD pkg names and reorder
Fortunately, there is a pattern to most of these package names
in all distros I've tested (and hopefully other BSDs have them,
too).
Then, reorder the INSTALL document to mention the top-level
modules, first, so users can avoid needing to type extra
dependencies. However, we still list some implicit dependencies
in case the upstream package drops dependencies independently of
us.
Finally, Devel::Peek is not a dependency worth making optional
since it's bundled by Perl upstream. Fedora/RH-based distros
are the only one which turn it into a non-standard package when
Perl5 is installed.