bird4: also exchange routes from dn42 and chaosvpn locally
bird4: do not add route to local mesh to table 42

as this interferes with the route added by the post-up
script of the mesh interface
bird4: remove additional blank line from generated local config
bird4: add new parameter depicting the whole ipv4 range of a community

as this might be different from the range used in the mesh. e.g. in hamburg
we use a /18 in the mesh whereas our range is /16.