Templates are now constructed with their precedence.
Variables are too, with a tweak to allow for the immediate evaluation of non-topl-level params and vars.
The execution context now no longer needs to track variable precedence, which is good because it will be getting it wrong anyway.
Corresponding simplifications follow to compliation context.
fixed internal qname resolution - 2.4 says unprefixed names are not in the default namespace
fixed xsl:element - unprefixed names, when no namespace uri is supplied are in teh default namespace
