Port devmanual to tyrian theme.

[anthonyryan1]

In addition to the theme conversion. I have fixed anchor links and removed a few now-unused methods from devbook.xsl.

A few additional points:

1. The content is XHTML, but it's being served on devmanual.gentoo.org with the html mime type. application/xhtml+xml might suit the content better. I haven't tested the entire manual making this change myself, but all well formed XHTML will work with that mime type.
2. The LICENSE file says this is CC-by-SA 2.0. The default on Gentoo properties right now is CC-by-SA 3.0. Can we port this, or should we change the Tyrian footer for this property.
3. This puts a sub-section index on the sidebar of every page. This is currently redundant on many pages that already have a subsection list within their content body. My thoughts here are to eliminate the necessity for content lists within text.xml files, and eventually remove them at a later date.

[a3li]

Did you see https://bugs.gentoo.org/show_bug.cgi?id=515696 ?

[anthonyryan1]

I had not seen that actually, I should have looked. The rollout page on the wiki for this project said that was not started and not scheduled anytime this year: https://wiki.gentoo.org/wiki/Project:Website/Tyrian/Rollout

I'll close this pull request and leave it up to the people already working on this. You're certainly welcome to borrow anything if you find it helpful. I just thought I'd give this a shot since I was working on #19.