Release 2.0.0

[iteman]

• Write wiki pages.
  • The overview
  • The release notes
  • The user guide
• Update build.xml and package.xml and commit on git.
• Update the PEAR channel.
  • Build the PEAR channel.
  • Upload the package to pear.pieceframework.com.
• Tag the release on git.
• Tweet the release.