Adds assertions for checking thread-safety.
Tidy.
Work on CBLDocument (ReactiveCouchbaseLite).
WIP on CBLDocument (ReactiveCouchbaseLite).
WIP on CBLDocument (ReactiveCouchbaseLite).
Improves usability of CBLManager (ReactiveCouchbaseLite) methods without starting from +[CBLManager rcl_sharedInstance].
Improves -[CBLDatabase (ReactiveCouchbaseLite) rcl_inTransaction:].