Port devmanual to tyrian theme.

In addition to the theme conversion. I have fixed anchor links and removed a few now-unused methods from `devbook.xsl`.

Two points worth noting while I'm looking at this:
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.