[xml] xmlUnlinkProp, xmlAddProp

["Petr Kozelka" <pkozelka centrum cz>]

Hello Daniel,
another two things that would help me implement the standalone DOM attribute wrapper:

- xmlUnlinkProp(xmlAttrPtr): a function that unlinks an attribute from the tree, without destroying it; 
(perhaps this would fit well
into the
existing xmlUnlinkNode?)
- xmlAddProp(xmlNodePtr, xmlAttrPtr): function that adds an existing attribute node to the specified element 
(should this be part of
xmlAddChild?)

Again, I didn't find this functionality in any existing API, hopefully I didn't miss it somewhere
My time is over for today, but if you are interrested I will create and send you patches tomorow; please tell 
me the preferred
alternatives.
Petr