Generate backlinks

To embed backlinks in a wiki page, use the following syntax:

Some text.

__BACKLINKS__

Some more text.

When you run the script, it will replace the __BACKLINKS__ marker with a list of linked pages, like this:

Some text.

<!-- backlinks:start -->
<!-- some more comments -->

## Pages that link here

- [[Page 1]]
- [[Page 2]]

<!-- backlinks:end -->

Those new placeholders will be replaced with the actual list of backlinks when the script is run next time.