it doesn't really gain us much to have a handful of
boost::signal use in a sea of Links

This also fixes a regression in

commit 051b29e1
Author: Luboš Luňák <l.lunak@collabora.com>
Date:   Sun Sep 14 15:45:02 2014 +0200

    convert Edit autocomplete Hdl to boost signals2

where the conversion was...

- if ( maAutocompleteHdl.IsSet() )
+ if ( autocompleteSignal.empty() )

instead of the correct

+ if ( !autocompleteSignal.empty() )

Change-Id: I27270d94c782485c0a7e929bc4980af4527fe82b