Log Message:
Update ruby-redcloth to 4.2.0.

Major changes since 4.0.4:
* JRuby support!  [olabini]
* Added textilize ERB utility method. [edraut]
* Compatible with Ruby 1.9.
* Change to list attributes so you can give style/class to list items.
* Ruby 1.9 string encodings are preserved
* Table cell parsing has been enhanced to handle empty cells and cells
  containing text with line breaks
* A major regression in the handling of notextile blocks has been fixed
* There is better handling of quotes inside quoted phrases, question marks
  inside citations, etc.
* Numerous LaTeX fixes thanks to NASA scientist Bil Kleb.
* A pure-Ruby version of the state machine for those that absolutely can't
  compile the C extension or use the precompiled JRuby or Win32 binaries.