adopt-project.py: plan's follow-up git grep takes a spec directory as its pattern and each code entry as a literal path, so a spec directory named -notes/ or a code entry named :cache/ no longer loses its follow-up, a code entry named */ no longer names a spec-leg file, a name outside ASCII is spelled instead of C-quoted, and a spec directory named -O<cmd>/ no longer runs a command (#216) - #228