For PIU: option to allow specific counts of single/double charts

[noahm]

Pump tournaments sometimes have draws which mix together Singles and Doubles charts, especially in later stages of a bracket. In the past they have used fixed counts (e.g. 4 singles, 4 doubles) for each mode. This app currently lets you mix the two modes in a single draw, but there's no way to constrain the amounts per mode.

[noahm]

This could potentially be implemented on top of #268 by allowing two separate configurations (one for singles, one for doubles) and somehow executing separate draws with each, merging the resulting cards together into a single drawn set. (or simply give an option to easily merge two sets of adjacent drawn card sets)