Added more logging to the learner
Added some logging to acceptor
Fixes in proposer

iid is not not memset to zero upon instance reclaim.

Proposer now starts from highest finalized. If the system has initial
state, acceptor will have highest finalized set as zero. This leads to
proposer skipping instance 0 altogether. Proper fix should be done in
the acceptor, i.e. rename the highest finalized to lowest non-finalized
with appropriate semantics change.