-t N parameter for fedaserv (the fd for the tun iface, created by the parent)

``associate'' command in the console (go associate with the given peer)

commands in the console to add/remove/disable/enable a peer

Implement ban list for IPv4 addresses (regardless of ports), prefix-based


[DONE] Correct the ``proposal'' to reflect the 0xfe's point role

[DONE] fedaserv: Refuse to run with point #0

reimplement the moment of association of a peer with a node/point as a
separate function, check the configured peers

[DONE] Introduce the "permanent" peer type, revise the policy of
determining if we need a connection

[DONE nodenets] "nodespace" peer type

[DONE] "ncc" and "introducer" peer types

[DONE] implement asking ncc's about node certs, and with the same dgrams, asking
the node by the point

[DONE] Implement full support for debug2 level
    - in servlog
    - in messages

[DONE] rename fsrv_knw into knowndb; get rid of calls to functions from
       fk_known; keep it NOT printing any diags

[DONE?] in knowndb move minpref from the node file to a special file (info?)

[DONE?] add everywhere the master_hsign field and its handling

[DONE] reimplement ``fedakeys signverify''

[DONE?] on point deploy, add the node and the point to the local known database

[DONE] don't demand kex keys for the export command

[CNCL] on mpoint and zcrpoint, create the .pub file together with the .key file

[DONE] finish the NC_SERVERS text




fedakeys: implement lock/unlock/anonlock


NB: https://www.man7.org/linux/man-pages/man7/rtnetlink.7.html (about ip
addresses on interfaces and routes)

NB: https://www.man7.org/linux/man-pages/man7/netdevice.7.html (interface
up and set the address on it)
