qr.py: fix import for 2.7
test_graphics_barcode.py: ensure QR gets tested
barcode\widgets.py: attempt to fix up widget construction
test_graphics_barcode.py: fix so we call createBarcodeDrawing on everything
barcode\widgets.py: clean up class construction
test_graphics_barcode.py: run all the widget test values
utils.py: add enc(oding) argument to asNative