Implement <perl>, <python>, and <ruby> tags.
* lisp/muse-publish.el (muse-publish-markup-tags): Add <perl>, <python>,
and <ruby> tags.
(muse-publish-command-tag): Code indentation.
(muse-publish-perl-tag): New function that publishes a <perl> tag.
(muse-publish-python-tag): New function that publishes a <python> tag.
(muse-publish-ruby-tag): New function that publishes a <ruby> tag.
* muse.texi (Tag Summary): Document <perl>, <python>, and <ruby>.
* examples/johnw/publish-johnw: Add explanatory comment.
git-archimport-id: mwolson@gnu.org--2006/muse--main--1.0--patch-172