With the stock system being deprecated now, we should provide
meaningful accessible names for buttons that are constructed
from icon names or GIcons. This commit reuses the existing
translations.
It is possible that some common icon names are not covered
here because they were not present as stock items. These can
be added to the table later.
This commit exposes the get_type() functions and standard
headers for accessible implementations. This makes it possible
to derive from the GTK accessible implementations without
GType magic tricks. This is necessary, because we require the
a11y type hierarchy to be parallel to the widget type hierarchy.
So, if you derive a widget and need to adjust its a11y implementation,
you have to be able to derive its accessible implementation.
This commit probably exposes more than is absolutely necessary,
it also exposes accessibles of widgets that are unlikely candidates
for deriving from.
