refactor: extract method output_chaps_by_file
HTMLBuilder: support PART file
Merge pull request #125 from takahashim/support_part

Support part in review-epubmaker
LATEXBuilder and HTMLBuilder: add new command //olnum[]

define initial item number in ordered list
fix #125 use relative path, not absolute (broken image)
fix #127 fix cover image metadata in OPF (for iBooks)
Merge pull request #126 from takahashim/add_olnum

LATEXBuilder and HTMLBuilder: add new command //olnum[]
Add hr to latexbuilder
HTMLBuilder: strip ReVIEW tag in <title>
modified for Ruby 1.9
experimental support for chaplink in IDGXMLBuilder.
escape chap id when chap includes - or + character.
review-preproc: add --tabwidth=WIDTH option
LATEXBuilder: add argment to use image_label()

it's not used in default template, but you can use it with
\renewcommand{\reviewimageref}.
support escape in footnote arguments
fix test
escape only \]
support --tabwidth=WIDTH option in review-compile
fix not to remove backslash in command argument
add more tests