I previously requested an API to remove redundant NS declarations in bug 120981
(http://bugzilla.gnome.org/show_bug.cgi?id=120981).  In response, a new parser
option (nsclean) was added in 2.6.0.

That's fantastic, but what I now find myself wanting is the ability to apply
such NS cleanups to a DOM tree itself at a later stage, after parsing.

The problem is that after building a DOM tree (with NS's cleaned up), some of
the manipulations that I make later (inserting new nodes etc) can introduce
redundant declarations again.

I would like to be able to clean up such declarations before I write the tree
back to a file.  At the moment the only way that I can write out a "clean" XML
file is to write the DOM tree once (just to a string suffices), then reparse it
using the nsclean parser option, then write it out to the file for real.

It would be great to have something like a xmlNsClean() function that can be
called on the DOM document before writing the file.

Alternatively, perhaps new xmlSave*() functions (or new options for existing
functions) could be introduced to do the clean-up as the file is being written.

- Steve