https://live.gnome.org/GeditPlugins
$ sudo apt-get install gedit-plugins
https://github.com/dtrebbien/gedit-trim-trailing-whitespace-before-saving-plugin
$ git clone git://github.com/dtrebbien/gedit-trim-trailing-whitespace-before-saving-plugin.git
$ cd gedit-trim-trailing-whitespace-before-saving-plugin/src