Support the 'packages' profile file as a directory

This adds proof-of-concept support for bug #282296. Current behaviour
without this change is to print a traceback.

Reviewed-by: Alexander Berntsen <bernalex@gentoo.org>
Make b4d8e300c04b768be7cd5c respect max line width
Bug #510538: Include "::repository" in more messages.
ebuild-helpers/xattr/install: use the binary wrapper if available; fall back to the python one

Signed-off-by: Gregory M. Turner <gmt@be-evil.net>
xattr/install helper: put /usr/bin at front of path to avoid invocation-bomb

Signed-off-by: Gregory M. Turner <gmt@be-evil.net>