Drop snapshots

I don't think they have been really used and building inside a tmp
symlink seems to be causing dbus processes to be leaked.
Remove snapshot make target too
Drop distribute stuff that I never really finished
Fix leak of dbus processes on check
Add pyflakes
Use 3.8 gnome-keyring

So we get consistent behavior on all distros.
Ignore sigint

Suggest to close sugar instead.
Fix pep8
Add sugar-html-graphics
Add xkl typelib dep
Fix ubuntu/debian xkl packages
Switch to github sugar-docs
Switch to github sugar-runner
Enable SUGAR_DEVELOPER

It will allow to close the session with keys.
Remove branch

We have a tag already.
Build keyring after glib