Renamed test module for managers.
Fixed query set for later tasks. Modified query set for done tasks. Revised comments.
Added tests about marking tasks current or done after archival.
Ignore marking reminders current or done and remove history entries when reminders are marked not done. Cleaned up some white space in comments.
Added tests for history to check that reminders can have exactly one history entry and routines can have multiple.
Corrected done time method in task model so that it also applies to archived routines. Added a unicode method for History.