* register vc duties with subnet tracker
* fix activation logging during startup
* cache slot signature to avoid duplicate signature work
* schedule aggregation duties one slot at a time to avoid CPU spike at
each epoch
* lower aggregation subnet pre-subscription time to 4 slots (lowers
bandwidth and CPU usage)
* update stability subnets in ENR on startup
* log gossip state
* perform gossip subscriptions just before the next slot starts
* document stuff
* add random include
* don't overwrite subscription state when not subscribed
* log target gossip state
* updating gossip status once is enough
* add test
* remove syncQueueLen - this one is not updated at the end of the sync
and may cause gossip to disconnect itself completely - use a simple head
distance instead
* fix gossip disconnection - if in hysteresis, node.gossipState will be
set to disabled even though we don't disable topic subscriptions
* fix extra duty registration call
Jacek Sieka