Don't use g_source_remove for signal handlers

This fixes reliable crashes when changing bookmarks or the read later
list if any single window has been closed.
Version 3.11.91
Version 3.12.0
doap: update URLs
Fixed Russian translation
Updated Indonesian translation
yelp: check if running on X11 before running gdk_x11_* code

https://bugzilla.gnome.org/show_bug.cgi?id=708181
Updated Swedish translation
Merge branch 'master' into new-aday-design

Conflicts:
	src/yelp-window.c
Move some actions to the app menu
yelp-window: Use placeholder text on empty bookmarks list