Cancelling order now dispenses change on cardless orders

Fixing a couple of small timing issues

On order completion, change is dispensed

CoinChanger can now dispense arbitrary amounts

Full vend functionality works It's very basic and doesn't handle corner cases, but it was very cool to watch the order update to the 'processing' status and then update to the 'vending' status. I still haven't done this with it all installed in the machine, so no idea if it actually turns the motors with this version. We've made some heavy modifications to that class since the last test.

Vend button is enabled if there is enough money available to vend

Inverted the colors on the main window buttons I originally made the buttons have the color border and the white background when not pressed and then switched to one solid color with white text when pressed. This diff inverts that. If someone is colorblind then the enabled not-pressed button and the disabled button would look basically the same. Plus this honestly just looks better with the pressed action. In real life you would think of a button being pushed down and this gives a similar effect without the use of shadows. I did modify the row/col buttons here but they don't match that pattern. I did that for two reasons. One is that when it's a solid background, it tends to be overpowering. Part of that I think is that I used 1px black lines to separate the buttons so it all just blends together and doesn't look good. The other aspect is that you have a visual indication of the item you want to vend because you'll see it in the machine. Eventually we'll need to check product stock levels too and we might end up with the case that an item is visually there in the machine but the button should be disabled. That may prove confusing for people, but they'll probably just assume we miscounted the items in the machine.

Add Item button should be disabled for "processing" order status

Vending existing processed order seems to work now

Added "Update Order" endpoint No idea of it works currently. I'll need to build out some test data for it and then test it, so this may not work 100% but we'll see.