Remove all the roadblocks we've put up to keep implicit modifiers
out. Our importing code already handles them as a signal that says
'No modifiers, please!'. Now we just hope for the best and pass
things along.
This is necessary since some drivers won't produce any explicit
modifiers.
Trying to use it is a programming error, applications should have code
that uses real modifiers.
Also add a check to the formatsbuilder so our code doesn't include the
invalid modifier by accident.
We don't really know how to deal with it, so better force applications
to figure out what to do.
