What we have at the moment isn't really the same as TiddlyWiki
classic's shadow tiddlers, it's a much simpler system for excluding
tiddlers. We'll use the term "shadow" instead to refer to the way that
tiddlers in plugins behave, which is exactly like TiddlyWiki classic's
shadow tiddlers.
"Plugins" are bundles of tiddlers managed as one, "modules" are
JavaScript tiddlers with a module type identifying when and how they
should be executed.
