* [NOD-395] Write a test for the diffFromAcceptanceData crash.
* [NOD-395] Converted MultiBlockTxsAcceptanceData into a slice.
* [NOD-395] Fix failing test.
* [NOD-395] Populate multiBlockTxsAcceptanceData bottom-to-top.
* [NOD-395] Add comment to FindAcceptanceData.
* [NOD-395] Remove no-longer relevant note about probability in TestOrderInDiffFromAcceptanceData.
* [NOD-338] Recover indexer if it didn't work for a while
* [NOD-338] Recover indexer if it didn't work for a while
* [NOD-338] Recover indexer if it didn't work for a while
* [NOD-338] Add tests and move blockidhash.go to blockdag package
* [NOD-338] Delete index current block id when dropping index, and do some refactoring
* [NOD-338] Change comments
* [NOD-338] Change recover error messages
* [NOD-338] Fix comments
* [NOD-338] Fix comments and fix test name
* [NOD-315] Created acceptanceindex.go including boilerplate.
* [NOD-315] Disallowed calls to notifyChainChanges and getChainFromBlock if the acceptance index is not on.
* [NOD-315] Implemented the acceptance index.
* [NOD-315] Fixed serialization/deserialization. Added test.
* [NOD-315] Fixed/added comments.
* [NOD-315] Fixed copy/paste errors.
* [NOD-315] Added an empty line for readability.