* libxslt/keys.c libxslt/templates.c libxslt/transform.c
  libxslt/variables.c: Fixes bug #110023 reported by Mark Vakoc and
  other places where ctxt->document pointer may be used without
  checking it agaisnt NULL.
* tests/docs/Makefile.am tests/docs/bug-115.*
  tests/general/Makefile.am tests/general/bug-115*: added the
  example in the regression tests for that bug.
* libxslt/trio.h libxslt/triodef.h: update of Trio from Bjorn Reese
Daniel