events: proof of concept

[hdonnay]

PoC for a possible use of the toolkit/events package.

The idea is that for every piece of code that we want to emit an "event" in a "debug request" it does something like this:

• Emit 1 event
• Collect metrics-like pre-definied pieces of information.
• Flag an error return with an error "level" event.

Questions:

• Do other log levels make sense?
• How many events is too many?

[hdonnay]

I'm inclined to try the "wide log" style for these events. But does one want to actually see every rejected vulnerability and why? Or is that a log handler's problem?