Add support for multiple announce servers (fixes #677)

Somebody owes me a beer.
Sorry, I don't think any interval set on this timer is actually used.
It might be 0, as we always reset the timer before using it regardless.

And I am not sure I understand what you are saying, this is the announcement loop not the lookup loop.
We always wait for the `localBcastIntv`, I don't think we wait for any other timer if everything goes well?