Add syntax for using items only once #31
Description
When creating a new project it's often useful to only use terms once.
E.g. if you have a list of names or topics, you only want Seed to select from the list, but never show the same thing more than once.
We already have a syntax for re-using a selection:
{{ topic:one }}
I propose using the syntax for distinct elements:
{{ topic:~site }}
Internally what this does is generate a list of indices, one for each option, shuffled in random order. E.g. if a list of topics has 5 items the indices could look like this:
4 2 1 0 3
This implies that if you have 5 items, you can only use the {{ topic:~site }} token 5 times. If you use it more than 5 times, the list of indices is repeated (e.g. 4 2 1 0 3 4 2 1 0 3 ...).