Replace size options with a scale input

[KainMorgen]

The size option could be more customizable with a scale input.

The size dropdown should be replaced by a number input spinner (input field with up/down arrows). The spinners input is the percentage of the card size. Default value should be 100 = normal card size.

Minimum value should be at least 1. We don't want to divide by 0 to check how many cards fit on a sheet. Arrows (if included) should inc/dec by 1 (not below minimum) Maximum is optional.

[KainMorgen]

Note on the maximum:

For now we assume most users will work with A4 sheets. Since the default size prints 3x3 cards on A4, the first max is assumed to be 300% since that would print exactly one card on a sheet. If the algorithm calculates that the cards are too big and exactly 0 cards fit on the chosen sheet we might encounter errors!

The might have to be adjusted for other sheet sizes (A3, A5, american norms). The print results will be poor with too high numbers anyways, since scryfall only provides scans in a fixed resolution.

[aloisdg]

We will need a custom component. Current naive implementation: https://jsfiddle.net/odepyc3w/4/