Function: add_card_to_set

--Usage--
> add_card_to_set(card, set: set)

Add a [[type:card]] to a [[type:set]].

If the input is a collection, all cards contained inside will be added.

Returns true if a card was actually added to the set.

This is for use in the CLI.

--Parameters--
! Parameter	Type					Description
| @input@	[[type:card]]		The card you want to add.
| @set@		[[type:set]]		The set the card must belong to.

--Examples--
> # Create a new card and add it to the current set:
> add_card_to_set(new_card([]))