[xmlsec] Schema centric canonicalization

[Aleksey Sanin]

> I also think that most of their rationale for "why we need yet another 
> c14n mechanism" is bogus.  They want something that remains valid 
> across infoset translations and serializations.  Yuk. :)

Well, I guess that different applications need different c14n. I've seen 
one that
just stripped out all whitespaces between tags. Seems bogus but the guys
had a very good reason (legacy embedded system in the chain) to do this.

I don't have any current plans to implement schema centric c14n. As Rich 
pointed out
the LibXML2 schema support is not complete yet (thought it seems to me 
that some
parts of schema centric c14n could be implemented with current level of 
schema support
in LibXML2).

Aleksey