search for: gtk_about_dialog_add_credit_section

As preliminary steps in splitting virt-p2v to an own repository, continue making p2v more independent within libguestfs. This is accomplished by the following changes: - have only the authors in the about dialog, and read them from a local AUTHORS file - few more cleanups This is still not complete, although I believe most of the work needed is done, and it still makes p2v usable within