Bump GObject requirement

This allows us to use the fixed version of
g_signal_connect_object().
Update valgrind suppressions
Plug a test memory leak
Cleanup internal Python hooks code a bit
Split special envar setting into another function

This is required because they must be set before
gtk_test_init() but we need to change the log settings
afterwards as it will change them.

This also prevents GDBus from being used
internally by GFile.
Simplify finding the plugin manager buttons
Use g_test_{build,get}_filename()

This is prep for installing the tests, also bump the glib dep.
Remove old glib version checks

We now require a glib old enough that these
are not required anymore.
Set the libpeas-plugin icon as the icon for the demo window
Bug 727380 - Fix test suite to work on OpenBSD

Change the warnings so they can be checked properly in
the tests without relying on OS specific messages.
Add a test for missing peas_register_types() in a C plugin
Merge toplevel and window group handling

Also fix warnings when the toplevel GtkWindow wasn't found.
Removing window group handling from the plugin manager test

This is no longer required!
Don't update the plugin info in the model twice

It was already being updated when the plugin was
{un,}loaded by the engine because it connects to the signals.
No longer show the plugin's icon in the plugin manager

This didn't add much value but quite a bit of clutter.
Show the whole range of plugin icons in the about dialog

The about dialog only handled icon-names. This adds support
for icons shipped with the plugin and for stock icon (old feature).

Sadly, because GtkAboutDialog doesn't expose it's GtkImage
publicly we have to use terrible methods to get the icon into it.
Add tests for correct icon handling

This tests that we correctly handle the 3 icon types we
support and that we fail gracefully.
Deprecate PeasGtkPluginManagerView

This is going to be replaced by a GtkListBox.
Use gtk+'s icon helper for getting a pixbuf for the about dialog

The other method uses testing API which is terrible and
is only available in gtk+ 3.10.