Improve ruby-electric-mode.

* misc/ruby-electric.el (ruby-electric-hash): New electric
  function that expands a hash sign inside a string or regexp to
  "#{}".

* misc/ruby-electric.el (ruby-electric-curlies): Do not insert
  spaces inside when the curly brace is a delimiter of %r, %w,
  etc.

* misc/ruby-electric.el (ruby-electric-curlies): Insert another
  space before a closing curly brace when
  ruby-electric-newline-before-closing-bracket is nil.


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@40166 b2dd03c8-39d4-4d8f-98ff-823fe69b080e