message: Fix image fallback
diff: @@ -120,11 +120,15 @@ www/images/%: images/%
  # try to download images if not linked; images may not be up to date
  images/%:
  - if [[ -d ospray-doc ]] ; then \
  + if [[ -d ospray-doc/images ]] ; then \
  ln -fs ospray-doc/images ;\
  else \
  + if [[ -x "`which wget 2> /dev/null`" ]] ; then \
  mkdir -p images ;\
  wget https://ospray.github.io/$@ -O $@ ;\
  + else \
  + curl https://ospray.github.io/$@ --create-dirs -Lo $@ ;\
  + fi \
  fi
  