using QStrings in filter and format vecs. (#428)

using QStrings in filter and format vecs. (#428)

This includes:
our format list entry vecs_t,
out filter list entry fl_vecs_t and
our format interface ff_vecs_t.

Fix validation of options supplied with a format or filter.
Previously unknown options were only detected if all given options
were unknown.  Now any unknown option will be reported, irregardless
of any other options supplied.
The behavoir of ignoring unknown options is unchanged, they are ignored
except for the warning.