2013-05-12-12.26.29: src/lib/x-kit/xclient/src/wire/xtypes.api:  Make Xid an opaque type, added xid_to_int, xid_to_string.  src/lib/x-kit/xclient/src/to-string/: Eliminated xtype-to-string.pkg (which had only contained xid_to_string).