Makefile: clean target
Initial commit of a simple barcode scanner using GStreamer
scan_barcodes: Made it event based using Gtk Mainloop
scan_barcode: Refactored the message handler to a function on the class
scan_barcode: Made it quit on Ctrl+C
scan_barcode: Do not reply on the field number but the name
scan_barcode: Move the gst_init to the main
scan_barcode: Embedded the scanner in a GTK window

This was a bit tricky as the information on the Web, i.e.
http://www.pygtk.org/pygtktutorial/app-codeexamples.html
had old stuff.
https://wiki.ubuntu.com/Novacut/GStreamer1.0#prepare-xwindow-id
helped a little.
http://askubuntu.com/questions/157290/how-to-draw-on-mouse-click-in-gtk-drawingarea-using-pygi
too.
Created a GTK widget that you can hopefully reuse

A few peculiarities I needed to take care of were
using do_realize to wait for instantiation to make
GStreamer happy.
Added a do_unrealize in order to not make it crash on exit
MainWindow: Made it a GtkApplication
MainWindow: Added a App Menu with a quit and a not yet existing action
Merge branch 'gtkwidget'
Gtk Widget: Hooked map and unmap to stop the pipeline

I think it's better to turn off the camera if we don't need it.
Now, when switching the notebook tab, the camera turns off.
Made the QR reader expand in its notebook page
MainWindow: present() if the user executes a second time
Added a sample GIO Action

Only to see how it works.
barcode reader: exposed barcode in a on_barcode function

So you can get notified more easily when a barcode is available.
BarcodeReaderGTK: Emit a GObject signal on barcode

This is probably more GNOMEy.
I was wondering how to emit a signal with the GStreamer message as
second argument. What type would I use when registering the signal?
Connect to the barcode signal

also, a very early Key class was introduced. I'd be surprised if it
survives for long as it may not be very useful and has probably been
implemented multiple times already. Monkeysign must use something
similar.