* [NOD-641] Upgrade to github.com/pkg/errors v0.9.1 and use errors.As where needed
* [NOD-641] Fix find and replace error
* [NOD-641] Use errors.As for error type checking
* [NOD-641] Fix errors.As for pointer types
* [NOD-641] Use errors.As where needed
* [NOD-641] Rename rErr->ruleErr
* [NOD-641] Rename derr->dbErr
* [NOD-641] e->flagsErr where necessary
* [NOD-641] change jerr to more appropriate name
* [NOD-641] Rename cerr->bdRuleErr
* [NOD-641] Rename serr->scriptErr
* [NOD-641] Use errors.Is instead of testutil.AreErrorsEqual in TestNewHashFromStr
* [NOD-641] Rename bdRuleErr->dagRuleErr
* [NOD-641] Rename mErr->msgErr
* [NOD-641] Rename dErr->deserializeErr
* [NOD-675] Rename startHash/stopHash to lowHigh/stopHash
* [NOD-675] Fix typo
* [NOD-675] Undo go.mod go.sum conflicts
* [NOD-675] revert back to startHash for getChainFromBlock.
* [NOD-675] Revet back to startHash in getChainFromBlock leftovers.
* [NOD-675] Fix test name.
* [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.
