Feature: add C* tag to know which recipe has been saved to which custom preset

[tomsihap]

Child of issue !4

Given a recipe and a LocalStorage preferences system
When I click on a "custom preset" dropdown
Then I can choose on which custom preset (C1 to C7) I save the recipe

It will definitely help keeping track of which recipe has been stored into which custom preset.

PS: thanks for this nice work. I'd be glad to fork and participate to develop the features I've proposed. Feel free to keep in touch by email to discuss these topics if you will.