Most GNOME apps now have a standardized About screen with links
(not buttons) for credits, website and links. Lukas called these
'selectors', which I like - but inconsistently; as well as
generic gnome_selector_foo needles, we have some app-specific
needles, and some with 'button' in the name.
Let's always call these 'selectors', always use generic needle
names (since the same needles should match for almost all apps),
and have the one remaining case where we have a 'button' (the
credits button in Evince) be the variant case, handled by putting
'button' in the needle name, but using the same tag as other
needles.
Signed-off-by: Adam Williamson <awilliam@redhat.com>
