Sub-repository updates.
Added add-upstream and fetch targets to component/ Makefile - now can easily track upstream branches that haven't been merged fully.
Disabled debug by default in Bird builds (as it disables the fork to background, which then results in bad behavior of ttin scripts). Sigh.
Sub-component update.
6rd -> tunnel renaming effort.
Updated OWRT feed too.
Removed copying of use-pd file - it no longer exists (and is not relevant).