* Split timestamp calculation into separate fn for math unit testing
* Add failing test
* Fix failing test; also bump stakes to near expected cluster max supply
* Don't error on timestamp of slot 0
* Add blocktree timestamp helper functions and tests
* Flesh out blocktree::get_block_time
* Move stakes up into rpc to make testing easier; expand tests
* Review comments
* Add intermittent timestamp to Vote
* Add timestamp to VoteState, add timestamp processing to program
* Print recent timestamp with solana show-vote-account
* Add offset of 1 to timestamp Vote interval to initialize at node boot (slot 1)
* Review comments
* Cache last_timestamp in Tower and use for interval check
* Move work into Tower method
* Clarify timestamping interval
* Replace tuple with struct