recent update-plist changes

It's still churning around. Loads of small recent changes. A summary of
what I'm remembering.

- the newuser/newgroup checks found quite a few (6 or 7) ports which had
forgotten to register their users in user.list.
This is actually quite bad from a security standpoint, as it means reusing
the same id for two things (especially for ports that hardcode ids), so
the warning has been removed and upgrade to an error in pkg_create (coming
soon to a snapshot near you)

- @rcscript are no longer "special" (again, source snapshots), so
update-plist will no longer dispatch them at the end of the plist, but in
alphabetic order, e.g., very often near the top, as
/etc/rc.d is before /usr/local.

- sanitization of paths like @extra /usr/local/some/file
(@extra still uses cwd, so it doesn't need the /usr/local)

- warnings for compressed/pre-formatted manpages, along with more general
.orig warnings.

- this can actually be turned off by adding
@comment intentional<somereason>
after the entry
.e.g.,
@man some/page.0
@comment intentional: port ships with preformatted pages

- tagging of fontdir, mandir, infodir, bin, libraries is way more accurate,
there's no reason not to heed those. Watch out for entries trying to
remove info's dir manually, or whatis.db, or similar files. (I may add a
rule that watches out for those in action and warns about it)


There are still issues left to fix:
- approximate placement of new files is not yet okay when the same directory
appears in several PLISTs. It may appear random.
- %%frag%% tend to move a lot in random ways...

And new features on the way:
- tweak fake wrappers for install/chown/chgrp to log attempted owner changes
that update-plist would grab, and try to make sense of to actually propose
@owner/@group changes by itself.

and maybe more, I don't know yet.