* [NOD-669] Remove the "get" from getBlueBlocksBetween.
* [NOD-669] Remove the "Get" from GetBlueBlocksHeadersBetween.
* [NOD-669] In blueBlocksBetween, rename startHash to lowHash and stopHash to highHash.
* [NOD-669] Rename startHash to lowHash and stopHash to highHash in blockLocator logic.
* [NOD-669] Remove zeroHash logic in blockLocator.
* [NOD-669] Finish renaming startHash and stopHash in blockdag.
* [NOD-669] Rename startHash and stopHash in blockdag where I previously missed it.
* [NOD-669] Rename startHash and stopHash in blockdag where I previously missed it some more.
* [NOD-669] Rename startHash and stopHash in blockdag where I previously missed it some more some more.
* [NOD-669] Fix bad grammar in method names.
* [NOD-669] Rename lowHash to blockHash in SelectedParentChain.
* [NOD-669] Fix a comment.
* [NOD-502] Remove checkpoints.
* [NOD-502] Remove remaining references to checkpoints.
* [NOD-500] Split RejectFinality to RejectDifficulty.
* [NOD-500] Remove support for headers-first in p2p.
* [NOD-500] Panic in newHashFromStr in case of an error.