Merge pull request #34 from Somasis/ng

OpenBSD pkg_tools support
Merge remote-tracking branch 'remotes/somasis/ng' into ng
README: add #pkg_tools support
pkg_cache safety checks i thought i pushed
Merge branch 'ng' of git://github.com/icy/pacapt into ng
Merge pull request #35 from Somasis/ng

Add safety checks to pkg_tools cache clearing
Merge pull request #37 from Somasis/ng

pkg_tools: add support for -Sl, clean up -Sy/Su a little