working on external leader
working on node-centric paxos
completed basic node implementation using messenger interface
working on heartbeat node
fixed unit tests for node-based heartbeat module
renamed node classes
separated pickle support into a dedicated mixin class
added explicit nack support and corrected some parameter names on the messenger interface
bugfixes
set leader attribute to false on detection of leadership loss
added leader lost transition on recipt of enough accept nacks
modified proposal_id value calculation
merged accept nack conflict
Moved durability/pickleability directly into node class. Added a retransmit function for accept messages
Switched to using explicit node_uids in all non-broadcast send/receive functions
bugfixes
added ability to change quorum size
merged resend_prepare functionality into prepare
revamping test code
added prepare nack