Please add vertical style for vertical writing

This branch add the following features:

 * Add "vert" and "horiz" text tags
 * Add ttgsubtable to get vertical glyphs (some fonts uses different glyphs on vertical writing)
 * Inherit vertical style on ruby and hyperlink
 * Draw underline to the right side of the vertical text

Screenshot:
http://ubuntuone.com/5yzbNUwlee3NsssPu4RkOy
Example script:
http://ubuntuone.com/1yCpuKSeDYXYb0nrhwCHZG