Branching Glade 3.6 line

[Tristan Van Berkom <tristan van berkom gmail com>]

Created a stable branch for Glade 3.6 today, the branch is called 'glade-3-6'

I hope to make releases off the 3.6 branch for a while and only use master
for some patches that are not release ready just yet, or patches which may break
string/ui freezes.


Cheers,
     -Tristan