delete all keys from a given block

[joshua-roberts]

Explore the possibility of creating a method such as deleteKeysFromBlock(blockNum) where we can delete all the keys from a block. It would probably only delete keys that exist in blocks that come after the given block otherwise it would delete the only write and therefore would not be included in the world state.

There could also be a method to delete the key(s) from the last N blocks that write the key(s).