[jdom-interest] getProperty/setProperty on Parent

[Jason Hunter]

> Should Parent define getProperty/setProperty so extra info can be carried
> with both Document and Element?

I was a little worried about carrying around an extra pointer on every 
Element.  On every document, it's fine.  But every Element?  Course, if 
we did that it'd be a place you could have a builder put a source line 
number, base uri, and other extensible features.  Choose in your builder 
which special data you want stored with each element.

> Should the javadocs then note that id's beginning with http://www.jdom.org
> are reserved for jdom use?

Done.

-jh-