Sum amounts when the same ingredient is mentioned multiple times.

[FranGarc]

I have this recipe in which you use (veggie stock or water) in different moments, with different amounts each time. For example, the first instance I use @liquid{0.5L} and the second time @liquid{0.75L}. The ingredients list should list "Liquid: 1.25L" instead of instancing Liquid: 0.5L and Liquid: 0.75L separately.

I'll include the recipe as an example: https://pastebin.com/2n6QSTR2