Merge pull request #789 from skinder/master

pkg add: PKG_FLAG_FORCE->PKG_ADD_FORCE
Update docco on how to build from source to reflect the new autotools
reality.

Fixes #788
Merge branch 'master' of github.com:freebsd/pkg
Fix repos without signatures support.
Use the PORTSDIR config variable when generating ports INDEX output,
rather than hardwiring '/usr/ports' into the code.  All the world is
not FreeBSD and ports can be elsewhere on different systems.
Document the -I option, a shorthand <query-format> used to generate
ports INDEX lines.
Sync the pkg.conf.sample with the currently allowed list of
configuration variables.
Add conflict chains to a problem in a proper way.

This commit fixes an issue when a universe item could be added
incorrectly, e.g. with missed parts of a conflict chain. That could lead
to endless loops in the solver.
Fix another bug in converting job->sat.

Items from install or remove request should also be added as a complete
conflicts chains.
Do not print rules to sbuf is debug is not enabled.
Do not require libraries that are provided by the same package.
Add some debug when adding shlib deps and provides.
Try to find provides in a more relaxed way.
Release 1.3.0.a10
Rework structures to allow multiple names.
Free name entries.
Add entry expansion function.
Do not free items in reference entries.
Update parser code for multiple names support.
Merge branch 'audit-rework'