Allowing incrementing item qty by doubleclicking on an item and checking allowNegativeStock setting to allow zero or less stock level sales.
Allowing final stock to be negative at the purchase dialog, adding a warning message.
Merge commit 'a884fde5fe44e892f627f2fb134e872ee203e79a' into ben2colima
Merge commit '037b1dabb5e8450a56f16d678177296ea075bde6' into ben2colima