Only print once a bad abi during pkg update

Reported by:	tuxillo (#dragonflybsd on efnet)

Conflicts:
	libpkg/update.c
Implement pkg audit -q
Add periodic scripts converted from pkg_install
Add $PREFIX to pkg command
Add "is pkg used" check
Simplify return code handling
Minor improvements
Rename 460.chkpkgsum to 460.pkg-checksum for uniformity
Fix bunch of typo and copy/paste mistakes. Remove redundant comments
Add bash completion script
Youps, my first pull was corrupted :o
Manually port various fixes to the shlib analysis code to release-1.0.
Direct commit because too much else has changed in master to be able
to merge easily.
Force reinstallation of a package is the required dependencies has change.

Testing the list of dependency origin between installed and remote
allows us to catch default version of perl/postgresql/mysql/etc change.

Waiting for new solver that reduce number of manual user interaction

Conflicts:
	libpkg/pkgdb.c
Fix dependency origin comparison commit
Reinstall port in case the required shlibs has changed

Conflicts:
	libpkg/pkgdb.c
make pkg install and pkg upgrade work again :)
Always activate shlibs (keep the options to not break ABI)
pkg_shlibs_required does not yet exists in 1.0
Set user agent
Copy the major,minor versioning thing used for repo.sqlite.

This means an older version of pkg can tell if it is compatible with a
new version of the local.sqlite schema.