Add preproc subcommand. see #6267

git-svn-id: http://jp.rubyist.net/svn/rurema/bitclust/trunk@5855 018432c1-2f1c-0410-ba7c-d424024924b7
Update description of preproc subcommand

git-svn-id: http://jp.rubyist.net/svn/rurema/bitclust/trunk@5856 018432c1-2f1c-0410-ba7c-d424024924b7
Add extract subcommand. see #6627

git-svn-id: http://jp.rubyist.net/svn/rurema/bitclust/trunk@5857 018432c1-2f1c-0410-ba7c-d424024924b7