Map Of London

Fixed a bunch of issues in XSLT, including adding handling for page breaks, and making TOC generation proceed one level further into the <div> nesting.

I've made a number of schema-related changes:

• XInclude elements are now integrated into the schema.
• The content models of <listBibl> and <listPerson> now allow a single <xi:include> element instead of other content. This makes pages like sources.xml valid, where they weren't before. The expectation is that we will extend the use of <xi:include> into other areas, to allow the centralization of editorial and encoding declarations etc.
• A Schematron schema has been created, which imposes a restriction which may or may not be permanent: <milestone> and <pb> are not allowed inside <hi>. This is to avoid HTML invalidity because of the inclusion of HTML <hr> elements (generated for page breaks) inside <span> elements (generated from <hi>s). Some instances of this have been fixed in a few files, which have had the Schematron schema PI added to their headers. Eventually this will be done for all files, and we will use Schematron for the sake of convenience.