The Emacs and Jed info readers don't like my index format: Info menu

The Emacs and Jed info readers don't like my index format: Info menu
items of the form `* stuff: Section 1.2.' are parsed by standalone
info as `Section 1.2' followed by a period, but are parsed by other
readers as `Section 1' followed by a period and then some spare
text. Therefore, I've changed strategy, and the index is now full of
*Note cross-references rather than menu items. On the plus side,
this means there are no longer any special characters which we can't
tolerate in an index entry; on the minus side, my shiny new
infrastructure for tracking the filepos of index entries is now
rendered pointless. I'll leave it in, though, since it may come in
handy again.

git-svn-id: svn://svn.tartarus.org/sgt/halibut@4053 cda61777-01e9-0310-a592-d414129be87e