Function: get_cards_from_link

--Usage--
> get_cards_from_link(input: card, linked_relation: "link type")

Inspects a given [[type:card]]'s links to find those of the given type, and returns an array containing the linked cards.
Returns an empty array if no link of the given type, or no card was found.

--Parameters--
! Parameter	Type				Description
| @input@	[[type:card]]		The card whose links we'll inspect.
| @linked_relation@	[[type:string]]		The type of link we want to find.
| @set@		[[type:set]]		The set in which to look. This can be omitted since 'set' is a predefined variable.
