Parsoid/HTML based LST

1-line summary: Use HTML-supported section tags with valid opening and closing tags rather than the self-closing section-tags.

Issues that need to be resolved

See also: Bug 69331
Paragraph merging across original pages: Text stored as single wiki page per original book page, with paragraphs potentially broken up. When reading, the page breaks should not be visible.
Transclusion is primarily by chapter (?) but there are other use case (dictionnaries...)
- which kind of transclusion is used there? Other kinds of overlapping sections? -- probably straightforward, no mis-nesting

Content of Page:Foo/1

  Foo
  
  beginning of

Content of Page:Foo/2

  <section begin=chapter1/>
  paragraph
  <section end=chapter1/>

  <h2>Chapter 2</h2>

Result of "{{Page:Foo/1}}{{#lst:Page:Foo/2|chapter1}}"

   Foo

   beginning of paragraph