monitor: Add example callbacks that store state
Store latest tree head; and all matching entries that matched the monitor's configured public keys. As discussed, might be nice to make, e.g., the updating of the signed tree head state into a library function.
Remember to think about: is it safe to start+stop (ctrl+C) and then not loose any state?
Also add leaf index to callback.
I'm also confused by the "size" output in the leaf callback. Perhaps remove, or rename to number of newly found leaves or similar?
Edited by Rasmus Dahlberg