Added newer jQuery attempting to fix bugs. Did not work but might
as well keep it available. Still configured to use 1.8.3 for now
since supposedly 1.9.x introduced major changes.
Revised javascript for supplementary pages that read from the
hardware driver. In most cases, these pages are looking for
scan data but other hardware messages should be run through
the parser so they aren't lost.
Pages descended from BasicPage should use a javascript callback
to handle messages from hardware. They also shouldn't request
scanner_scale_polling directly since it happens by default
(login3.php).
BUGFIX: automatic logging of products changes in prodUpdate via
ProductsModel needs to be aware of save() method calls that are
directed at the lanes rather than at the server.