ruby-additional.el: track by marker

* misc/ruby-additional.el (ruby-encode-unicode): use marker
  instead of offset to track insertion.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@46994 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
ruby-additional.el: change key

* misc/ruby-additional.el (ruby-encode-unicode): change key
  binding to get rid of conflict with uncomment-region.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@46995 b2dd03c8-39d4-4d8f-98ff-823fe69b080e