linking to signals

[Matthias Clasen <mclasen redhat com>]

I've recently started to use the #GtkWidet::expose-event syntax that was
introduced some time ago to create links to signal documentation. It is
really great to have this convenient syntax for it, but here are two
things that I think should be improved:

a) While it is necessary to specify the class to uniquely identify a
signal, in practice there is rarely confusion about which class a signal
belongs to. Therefore, I'd welcome it if we could simplify the formatted
link text in the output to just ::signal-name.

b) The link syntax moves ::signal-name closer to being the "official"
way to refer to signals in the docs. It would therefore be more
consistent if the autogenerated signal docs would also use ::signal-name
in their title, instead of "signal_name".

Opinions ?