Make gedit-mate compatible with G3

[ivyl]

Hi guys, currenly I'm before my exams so I don't have much time. This will last for about month. After that I will start porting plugins for gedit3, but until then I must ask you for help.

Here you have quite nice guide about new plugins: http://live.gnome.org/Gedit/PythonPluginHowTo

If you have some spare time start proting selected plugin (write your choice here, so work won't be duplicated).

It will be appreciated.