[tor-relays] avoiding frequent MyFamily syncing on a dynamic Tor instance group

[tagnaq]

Hi,

I don't know if this is already done but it just came into my mind when
writing something to sync MyFamily settings throughout multiple nodes:

To avoid frequent reloads of many Tor instances, one could pre-emptively
create keys (lets say keys for 30 nodes) and build a MyFamily set for it.
As you add nodes use this MyFamily set although not all 30 keys are in
use yet. This way one would not have to touch running instances when
adding new ones.