* [NOD-652] Add selectedTip and getSelectedTip messages
* [NOD-652] Remove peerSyncState.isSelectedTipKnown
* [NOD-652] Do nothing on OnSelectedTip if the peer selected tip hasn't changed
* [NOD-652] Handle selected tip message with block handler
* [NOD-652] Add comments
* [NOD-652] go mod tidy
* [NOD-652] Fix TestVersion
* [NOD-652] Use dag.AdjustedTime instead of dag.timeSource.AdjustedTime
* [NOD-652] Create shouldQueryPeerSelectedTips and queueMsgGetSelectedTip functions
* [NOD-652] Change selectedTip to selectedTipHash where needed
* [NOD-652] add minDAGTimeDelay constant
* [NOD-652] add comments
* [NOD-652] Fix names and comments
* [NOD-652] Put msg.reply push in the right place
* [NOD-652] Fix comments and names
