g_logv adds one for us already.
Use the 1.30 GLSL shading language for the fragment and vertex shaders. https://bugzilla.gnome.org/show_bug.cgi?id=756142
Since we dropped the legacy OpenGL compatibility profile, we need to use recent OpenGL APi and concepts. This also means that the example code gets a tad more complicated. https://bugzilla.gnome.org/show_bug.cgi?id=741946
This is a very simple test of GtkGLArea.
