si->sl transition done

the long-ago-threatened conversion of the phpdoc-si repository to
phpdoc-sl (reflecting the correct language code) was just completed. the
mailing list was simply renamed, so old subscriptions were carried over.

you can fix up a local checkout by renaming the 'si' directory to 'sl',
editing the top-level CVS/Entries to have 'D/sl////' instead of 'D/si////',
and then editing sl/CVS/Repository and sl/language/CVS/Repository to
refer to phpdoc-sl instead of phpdoc-si.

jim