fixed several consistency issues with y-indexeddb. Implemented support for .close() - a soft replacement for .destroy()

copy db, connector, and type properties before handing them over to the connector, etc. This prevents some weird errors using y-elements

repairChecker: Yjs is now able to detect incorrect states that happen when messages get lost. When Yjs is in an incorrect state it repairs itself and syncs again

found another bug that only happens in persistent databases (operationAdded changes an operation, so it needs to be retrieved again after calling it)