[FROG] BGP VPN-VRF route leaking per RFC 4364

[Donald Sharp]

All -

I'd like to thank Paul Ziemba, Lou Berger and Renato Westphal for
their work on getting FRR to allow BGP VPN-VRF route leaking.  This is
per RFC 4364.  The new syntax for this is:

router bgp <as> [vrf <FOO>]
    address-family <afi> unicast
        rd (vpn|evpn) export (AS:NN | IP:nn)
        label (vpn|evpn) export (0..1048575)
        rt (vpn|evpn) (import|export|both) RTLIST...
        nexthop vpn (import|export) (A.B.C.D | X:X::X:X)
        route-map (vpn|evpn|vrf NAME) (import|export) MAP

        [no] import|export [vpn|evpn|evpn8]
        [no] import|export vrf NAME

Further documentation can be found in doc/user/bgp.rst

thanks!

donald