Retrospective commit from 2009-10-17.

Retrospective commit from 2009-10-17.

Continue working on display of R2L glyph rows.  Reverse glyphs in
term.c:append_glyph rather than in extend_face_to_end_of_line.
Fix bidi iteration near BEGV and ZV.

 dispextern.h (struct glyph): New members resolved_level and
 bidi_type.

 xdisp.c (append_glyph, append_composite_glyph)
 (produce_image_glyph, append_stretch_glyph): Set them.

 term.c (append_glyph): Ditto.

 xdisp.c (display_line, next_element_from_buffer): Set the glyph
 row's reversed_p flag if the paragraph base direction is odd.
 (extend_face_to_end_of_line): Don't reverse the glyphs here.

 term.c (append_glyph): Reverse glyphs here.

 bidi.c (bidi_get_next_char_visually): Don't exit early when at ZV.
 (bidi_paragraph_init): Don't step over a newline if at BEGV.
 (bidi_paragraph_init): Handle empty buffers.