Fix memory leaks in property setting/getting
Fix memory leaks in property setting/getting

Do not leak GValues and string arrays, free them properly. As we always free
the intermediate GValues, use g_value_dup_boxed() instead of
g_value_get_boxed() when appropriate.

Detected by test_gi.TestPropertiesObject.test_strv test case.

pexip/pygobject,pexip/pygobject,davibe/pygobject,sfeltman/pygobject,davibe/pygobject,davibe/pygobject,pexip/pygobject,sfeltman/pygobject,GNOME/pygobject,sfeltman/pygobject,GNOME/pygobject,GNOME/pygobject,davibe/pygobject