* Implement removal of stale nodes from network
Add eventHorizon to NetworkParameters structure. Add republishing of
node info on 1 day intervals - it is treated by network map as heartbeat from node indicating if it's alive or not. Add removal of old node infos on network map signing.
* Add copy method to NetworkParameters data class
Add JvmOverloads annotation to the constructor, because it's data class
exposed in API
