[xml] adding "void *private" member to the struct xmlNs

[Aleksey Sanin <aleksey aleksey com>]

Hi, Daniel!

This question was discussed some time ago but I could not understand
do we have any agreement or not. And  I would like to raise it again
because it looks like I need this functionality too :)
So the question is: can we add "void* private" member to the "struct xmlNs"?
This pointer will be used by application to store application specific data
and LibXML will simply always ignore it.
There were two suggestions:
   1) make struct xmlNs  similar to structures for other node types and put
   "void * private" on the second place (adv.: simplicity and following
   standard; dis. : this breaks binary compatibility)
   2) add "void* private" to the end of struct xmlNs (adv.: binary 
compatible;
   dis.: "special case" for applications)
As far as I can understand, we could not go with option 1) because of 
binary
compatibility. I would like to find out, can the implement option 2) 
(it's ugly
but it gives me what I want :) ).

Thanks,

Aleksey