Removed couple of unused variables
Leader now does not send messages from ev callbacks
Fixed leader timeout flag not being set
Proposer now does not yield in ev callbacks

Instance timers are now using cond vars with separate fiber performing
the timeouting.

Switched to fbr_sendto instead of unwrapped sendto.

Also proposer now starts from highest finalized + 1 if local acceptor
is present instead of "always start from zero".