* resolveSingleBlockStatus: If the block being resolved is not going to be the next selectedTip - set it's diffParent to be the old selectedTip
* resolveSingleBlockStatus: If the block being resolved is going to be the next selectedTip - set it as old selectedTip's diffChild
* Remove any mentions of virtualDiffParents
* If block is genesis - don't do all the mumbo-jumbo with oldSelectedTip
* Check an unchecked error
* Write a better log message