Add new Lensfun geometry transformations introduced in 0.2.7. This fixes #9133.
lens.c: don't forget our ban on caps
Fix #9394: Enable ctrl-a and friends for filmstrip

This reminded me that we need to somehow remember the currently loaded
image in darkroom mode and not rely on the selected image when going to
the next/previous one using space/backspace. This breaks when no image
is selected ...