It turns out the cropper is _way_ too hard to use on mobile. The
cropper handles are much too small for a touch screen. Maybe I can
figure out how to improve the UX eventually, but for now, Tabitha
requested that we remove that functionality.
And now we come to the meat of the thing: the ability to update
transactions and attach receipts. Most of this is straightforward,
except for changing the amount of split transactions. Hopefully, this
won't come up too often, since I can't really split transactions without
a receipt. Just to be on the safe side, attempting to change the amount
of a split transaction will return an error.
Dustin