Libxo bugs and fixes.

[Phil Shafer]

Alfred Perlstein writes:
>In the case of xo_flush_h() how does a subroutine know how to flush the backing object o
>f the handle?

Okay, I buy the argument that calling xo_flush should trigger a
flush all the way down the stack.  The app should be able to
call xo_flush when it matters to the app, and the result should
be a complete flush of output.  Will get it working.

Thanks,
 Phil