using UserCtype in I/O test (was Re: test for lib.string.io)

[Martin Sebor <se...@roguewave.com>]

Martin Sebor wrote:
[...]
 > The next step will be replacing the
> ctype facet with the one in rw_ctype.h.

Here's a patch replacing the Ctype class defined in the test
with the new UserCtype template from rw_ctype.h. The patch
is against the current sources (as opposed to the patched
sources that haven't been committed yet) so I'm posting it
so as to avoid collisions.

Martin