r20601: Web Application Framework

r20601: Web Application Framework

More testing revealed that this isn't yet bug-free...  Sigh.  One of these
days I'll start writing bug-free software...

- Status and Statistics timer wasn't always stopped properly when switching
  away from that module's display.  It seems silly to continue to update
  status and statistics when the page isn't being viewed.

- Single instance of the Login window was not accessible if one switched
  between modules.

- Upon return from a Session Timeout, we can retry the original RPC request,
  but it may fail due to information that was stored in the old session.  This
  was the case in the LDB Browser module, where the open database handle
  became gone with the session.  We now detect a Resource Not Found and
  re-open the database.