* libxslt/functions.c: added some logic to xsltKeyFunction
to set the transform context doc ptr when the xpath context
doc is different (bug 147445)
* tests/exslt/common/Makefile.am, tests/exslt/common/node-set.5*
and tests/exslt/common/node-set.6*: added regression tests
for bug 145547 (UNION and FILTER for RVT's)