Add link checking for external StoryIncludes passages

Include a new StoryIncludePassages hidden passage that has tags for every
single passage that is contained within StoryIncludes passages. This is to
ensure that when using the external StoryIncludes, broken link emblems don't
appear on passages that link to these external passages. It's a bit of a hack,
but it seems to work well in having proper multi-file twine stories while still
keeping the convenience of the link checking.
Change version information from 1.3.5 to 1.3.6

Change the version that twine declares itself from the ancient version of
1.3.5 to 1.3.6 which is what all of the alphas have been declaring it as.
Update SugarCube and update link parsing to handle new return and back macro syntax

SugarCube has been updated, and with it, some fixes, and a new syntax to the
back and return macros, which enable the link text to be changed for each one.
This requires a bit of a tweak to the link parser to handle this new syntax.