Table of contents and section links

[ashes999]

Try Ruby is eight sections. Each section is not trivial to go through, even if you consider typing next 20-30 times. It's painful.

I assume Try Ruby will remain stateless for performance etc. reasons, so I'm proposing two changes:

• a contents or sections command that lists all eight sections, with a short (3-5 word) summary (eg. input/output)
• a goto x command to go to section x (by name or number)

This shouldn't be too hard, and I don't mind looking into how to do it ... except that there's a PR from December 2013 (#168) that's still open, so I doubt if my changes would ever be integrated.