Strips trailing whitespace and adds a trailing newline when an editor is saved.

To disable/enable features for a certain language package, you can use syntax-scoped properties in your config.cson. E.g.

'.slim.text':
  whitespace:
    removeTrailingWhitespace: false

You find the scope on top of a grammar package's settings view.

Note: for .source.jade, .source.diff, .source.pug and .source.patch, removing trailing whitespace is disabled by default.