Retrospective commit from 2009-10-04.

Retrospective commit from 2009-10-04.

Continue working on determining paragraph's base direction.

 bidi.c (bidi_at_paragraph_end): Check for paragraph-start if
 paragraph-separate failed to match.  Return the length of the
 matched separator.
 (bidi_line_init): New function.
 (bidi_paragraph_init): Use bidi_line_init.  Do nothing if in the
 middle of a paragraph-separate sequence.  Don't override existing
 paragraph direction if no strong characters found in this
 paragraph.  Set separator_limit according to what
 bidi_at_paragraph_end returns.  Reset new_paragraph flag when a
 new paragraph is found.
 (bidi_init_it): Reset separator_limit.
 dispextern.h (struct bidi_it): New member separator_limit.
 bidi.c (bidi_find_paragraph_start): Return the byte position of
 the paragraph beginning.
 xdisp.c (set_iterator_to_next): Call bidi_paragraph_init if the
 new_paragraph flag is set in the bidi iterator.
 bidi.c (bidi_at_paragraph_end, bidi_find_paragraph_start): Use
 the buffer-local value of paragraph-start and paragraph-separate.