Compute tariff prices as a discount from another tariff (CR 1102)
Some customers are defining child rates or season ticket holder rates as a percentage of a full rate. For example, the amount of the child tariff could match the full tariff with a discount of 40% (or 10€).
Currently only "no discount" or "fixed discounts" can be defined for a tariff
This feature adds a new discount possibility: tariff as a percentage of another tariff
