gsf api thoughts

[Jody Goldberg <jody gnome org>]

libgsf development is coming along.  Tambet has finished a first
pass at zip file import and has started on zip export.  It is now
trivial to add a wrapper which would support the OO style zip files.

Dom and I discussed a doc meta data api, and appear to have collided
on an implementation.  However, while playing with converting the
rest of gnumeric's export plugins to use libgsf I've come across 2
api issues that could use some imput.

1) gsf_output_printf (and friends)
On the input side I got a gsf_input_textline class to handle reading
text sources line by line (1 byte encoding or utf8).  That seems
reasonable.  Line by line text seems like a format.  On the output
side it is less clear.  It would be useful to have the printf
routine in the base class, but this introduces an asymetry in the
interface.  Any preferences ?

2) output unref vs close.  Should unrefing an output close it ?
I suspect so given that any other behaviour would be much harder to
implement.