Consider directory itself to be part of datafiles

Previously the directory name was just entered as part of a glob; the
new version uses the satellite name as a directory and also makes sure
that this directory is available to run tests in, even if there are no
datafiles (the directory itself is now considered a datafile)
Correct mixup between option and cache variables

Options are boolean flags that are stored... in the cache, whereas
cache variables are also stored in the cache, but can have a variety
of types (including booleans). It was possible to confuse the two,
because if you set it as a variable on the command line, it will
override both.