cache staking events instead of processing from scratch on every restart

[istae]

Like the title says, on startup, staking events should be processed from a local cache to speed up bootup time.

[ldeffenb]

Sounds like a good idea. First will likely come a command line option to skip the stake loading. monSI can discover "All Players" as they first show up with activity. Might even change the name from "All Players" to "Active Players" if all of the stakes are not loaded.