Update gedit3 to 3.6.1

- File Browser side panel improvements (Ignacio Casal Quinteiro)
- Fix print preview in landscape mode (Adrian Johnson)
- Handle a command line specifying a big line number (Paolo Borelli, David Toton)
mprovements in snippets plugin (Jesse van den Kieboom)
- Use autoreconf instead gnome-autogen (Javier Jard坦n)
- Extensive snippet collection for docbook
- Improved html snippets (Jaseem Abid)
- Misc bugfixes
- New and updated translations
c.f., http://git.gnome.org/browse/gedit/plain/NEWS?id=3.6.1

(prlw1)