====startup tag====

This special tag is similar to [[harlowe:header]], but it will only cause the passage
to be included in the very first passage in the game.

This is intended to simplify the story testing process: if you have setup
code which creates variables used throughout the entire story, you should put it in
a passage with this tag, instead of the starting passage. This allows you to test your
story from any passage, and, furthermore, easily change the starting passage if you wish.

All passages tagged with ''%%startup%%'' will run, in alphabetical order
by their passage name, before the passages tagged ''%%header%%'' will run.