LC-56: schemaPrefix

James Clark pointed out to me that XSLT actually had a mechanism (namespace nodes) for accessing the namespace mappings so it is possible to resolve QNames without additional information which
resolves my initial motivation for this comment.

However, I believe that some kind of hint of the anticipated prefix (suggestedTargetPrefix attribute on schema element?) would be useful in documentation generation and use by schema-aware editors.
For example, XSLT could suggest using "xsl", schema could suggest "xsd", etc.