* Add MIN and MAX for BlockHeight and LockTime
* Remove duplicate test cases
* fix a comment about the minimum lock time
The minimum LockTime::Time is 5 November 1985 00:53:20 UTC, so the first
day that only contains valid times is 6 November 1985 (in all timezones).
Similarly, the maximum LockTime::Time is 7 February 2106 06::28::15 UTC,
so the last day that only contains valid times in all time zones is
5 February 2106.
* fix: Reject checkpoint lists with bad hashes or heights
Reject the all-zeroes hash, because it is the parent hash of the genesis
block, and should never appear in a checkpoint list.
Reject checkpoint heights that are greater than the maximum block
height.
* Flatten consensus::verify::* to consensus::*
* Move consensus::*::tests into their own files
* Move CheckpointList into its own file
* Move Progress and Target into a types module
QueuedBlock and QueuedBlockList can stay in checkpoint.rs, because
they are tightly coupled to CheckpointVerifier.
teor
Jane Lusby