New tender options:
NoChangeTender does not allow change
NoDefaultAmountTender requires a typed amount rather than
defaulting to the current amount due.
Better error detection if db connectivity isn't available
$_SERVER['REQUEST_METHOD'] not reliably set apparently
Setting for printer driver class. ESC/POS is still the only thing
well supported in practice but an Epson printer that requires
slight tweaks should be easier to support and completely different
printers are possible if someone really wants.
Extra supervisor option to print other cashiers' tender reports
Remove "dev" from heading in header.html
Merge branch 'master' of https://github.com/CORE-POS/IS4C