tell cross-reference engine whenever we hit a verse.
register verse number after appending to paragraph so that it
can be attached to the vers number piece of the line, so that
if the line gets broken by the following word, the cross-reference
information will follow the verse number.
add crossrefs structure to line pieces to attach cross-reference
paragraphs to.
build hash table with every cross-reference paragraph.
find cross-reference paragraph for each verse.
fix some bugs in building cross-reference paragraphs
add crossref typeface to configuration.
remove crossreference_paragraph, and just use dynamically allocated
temporary paragraph when formatting cross-references.
create initial empty page so that HPDF_Page_TextWidth() works when
loading cross-reference library.
eliminate empty page at start, without messing up cross-reference
paragraph rendering.