apply-imports support:
- FEATURES libxslt/imports.h libxslt/pattern.[ch]
  libxslt/xsltInternals.h libxslt/transform.[ch]
  libxslt/templates.c libxslt/xslt.c:
  Added apply-imports, keep a stack of running templates
- libxslt/xsltutils.c: bugfixes, gather the output informations
  down the cascade
- tests/xmlspec/Makefile.am tests/xmlspec/REC-xml-2e.xsl
  tests/xmlspec/diffspec.xsl tests/xmlspec/xmlspec.xsl: running
  the real set of transformation on XML-1.0 2e generages a near
  perfect HTML. Needs just more number fixes and implementation
  and an obscure problem in 3.3.3
Daniel