The markdown_helper gem I've put up does (so far) one thing:

• Supports file inclusion.

I have in mind two additional features:

• Support for relative links for images (see below for why this matters).
• Support slideshow-style markdown pages (pages linked by next/prev navigation links).

Query: What else would be useful?

About relative links for images: they work fine in GitHub markdown, but when the project is formed into a gem, the links are broken in the gem's documentation. That's because on RubyDoc.info, YARD has rearranged some files and folders.

The workaround is to substitute absolute links to the files in raw.githubusercontent.com. This would be very inconvenient, not to say tedious and possibly error-prone.

What I want to add to the helper is a method that replaces the relative links with absolute ones automatically. That way, we have the convenience of relative links on GitHub, and correct (absolute) links on RubyDoc.