Add support for Bible, book and chapter introductions.

JSword and SWORD differ in their mapping of verse references to and from ordinal numbers. JSword needs to convert its ordinal number to SWORD's in order to find a verse in a module.

SWORD uses 0 to be the reference to an introduction.
A chapter introduction is verse 0.
A book introduction is chapter 0.
A testament introduction is book 0.
A module introduction is testament 0.

Where as JSword has Gen 1:1 as the ordinal number 1, SWORD has it as 5, with module, testament, book and chapter intros preceding it.

This effort needs to do the following:
Allow an explicit 0 in a reference for chapter or verse,
Allow chapter and testament introductions to be gotten (not sure what the syntax should be)
Replace JSword's ordinal mapping with that of SWORD's
It would also be good to:
Externalize/Serialize the mapping. (This will have to be done for JS-13)