Bump xwt
Bump xwt
Change output directories of platform add-ins

The platform add-ins are now generated in the bin dir.
Required since those add-ins now reference the platform-specific
Xwt.Gtk assemblies, and those need to be copied to the bin dir.
Updated references to xwt, md-addins
Updated references to xwt, md-addins
Updated references to xwt, md-addins
Updated reference to md-addins
Updated reference to md-addins
Remove redundant Edit button
Remove Xwt.Gtk.Mac and Xwt.Gtk.Windows from Linux build