Howdy!

I would like to contribute two patches for the Texinfo exporter:

1. Custom, or disabled, Texinfo navigation.

   This enables the user to, e.g.
   
   - put a top-level tree to a wider "Up" context, or
   - hide "Next" and "Previous" for a group of unrelated headings, or
   - build deeper hierarchies if needed.

2. Links in Texinfo section names.

   Importantly, this also applies to

     sub-`h:' headings,

   which are exported as plain lists.
   
   (Note: Links are a bit buggy on the Texinfo side, but that is not an
   Org issue; they are supported, and I find them useful.)
   
Thank you.

Rudy