Partial implementation of LinkSet.link().
More LinkSet.link() implementation. Found an issue.
Rename "fetching" status back to "loading".
Ditch LinkSet cloning and .directImportLinkSet.
Remove unused LoadTask.onModuleCompiled() in favor of LoadTask.finish(). Fix an unrelated bug in LinkSet.link(). Polish a comment.
Swap order of LinkSet and LoadTask in the source.
Check for module redeclaration at the top of LoadTask.finish(). This should be unified with similar code elsewhere; added a comment in @checkModuleDeclarations to that effect.