Minor changes to correctly define AUTHORED_RESOURCE.current _revision

Changes made: - to AUTHORED_RESOURCE.current _revision: add a post condition:     Result = revision_history.most_recent_version - to REVISION_HISTORY add the routines:     most_recent_version: String             -- The version id of the most recent item, as             -- a String.         ensure             Result.is_equal (item.first.version_id.value)     most_recent_version_time_committed: String             -- The commit date/time of the most recent item, as             -- a String.         ensure             Result.is_equal (item.first.time_committed.value) -- in the support.assumed_types package, add a minimal class    defintion for List<T>, that includes at least the routine    first: T