* api/*.xml : a few new attrs
* generator/Parameters.cs : remove redundant ref keywords
* gtk/ListStore.custom: overload SetColumnTypes
* gtk/TreeStore.custom: overload SetColumnTypes
* parser/GAPI/Metadata.pm : allow callback nodes at class level
* sources/Gtk.metadata : hide ClipboardClearFunc and GetFunc,
tag types param of SetColumnTypes as array, uncomment needs_ref
tags on Widget methods to match the current api.xml file
svn path=/trunk/gtk-sharp/; revision=9148