It seems I forgot to fix some usage of core gimp_vectors_export*(),
which now take a list of paths (not a single path anymore since commit
9fc8260c7c), as these were used by PDB functions.
The `precision` parameter in particular had no min/max, which meant we
could provide a forbidden parameter (e.g. a negative precision) which
would cause a core CRITICAL. We must forbid illegal values from PDB side
(hence outputting a normal plug-in error message, not a core bug).
Also improving a bit the description of this parameter as I was
wondering what precision was needed exactly to get a stroke length. This
is the precision for determining whether a portion of the stroke is
"straight enough" or if we want to break it into smaller pieces until we
get a straight portion.
and in an attack of madness, changes almost all file plug-in
code to use GFile instead of filenames, which means passing
the GFile down to the bottom and get its filename at the very
end where it's actually needed.
It never belonged inside "tools". Also rename its "pdb" subdirectory
to "groups". This had to happen before 2.10 so cherry-picking between
branches doesn't become a nightmare in the future.
Jehan