no need to change load_strategy_class's parameter; using accessor
change ReVIEW::Highlighter module to class
fix: unescape html in //source before highlighting
* highlighter should escape body if highlighting is not used
* highlighter should have a referece to builder (to use escape method)
review-epubmaker: support syntax-highlight in EPUB
fix test
do not call Builder#highlight method if no @highlighter
fix test
add 'color' option for Highlighter.new