This removes PKG_VERSION and PKG_RELEASE from most Makefiles, as the
value was never useful for Gluon packages; instead, PKG_VERSION is set
to 1 in gluon.mk.

It also removes two other weird definitions:

- gluon-iptables-clamp-mss-to-pmtu replicating the old PKG_VERSION logic
  from gluon-core, but without the fixed PKG_BUILD_DIR to prevent
  unnessary rebuilds
- gluon-hoodselector set GLUON_VERSION=3

The commit a0800497352e ("gluon-status-page-mesh-batman-adv: Retrieve TQ of
neighbors with non-best direct link") removed the check whether a neighbor
has the BATADV_ATTR_FLAG_BEST set. But consumers may still want to filter
out or mark neighbors which don't have this flag set. To assist with such a
feature, enhance the neighbor object with an extra boolean "best" attribute
which stores whether the BATADV_ATTR_FLAG_BEST was found or not.

Reported-by: Vincent Wiemann <webmaster@codefetch.de>

Links between two direct neighbors are not always the best route between
these devices. The flag BATADV_ATTR_FLAG_BEST would not be set for these
originator entries and the respondd module would just ignore this entry.

If these neighbors are not accepted and returned to the status page then
some of the neighbor entries will show a name, (acceptable) signal strength
and mac address but no TQ value.

Fixes: 28668c8c ("gluon-status-page: API")

batman-adv-specific parts are moved to a new package
gluon-status-page-mesh-batman-adv.