* codegen/defs-parse.pl (get_sighandler): gen the helper class. arg
passing and return value handling need beefing up still.
* glib/SignalArgs.cs : New arg passing/ return value handling class.
* glib/SignalCallback.cs (dtor): kill, this will be gen'd in the
subclasses. (ctor): prune down to two params.
svn path=/trunk/gtk-sharp/; revision=1438
