Apparently we were reading packed booleans wrong the whole time
(whoops!) They are packed into *bytes*, oops... That is fixed now, and I
also expanded write support for packed booleans. It makes the assumption
that the byte is always at the end of the row, but I think that's OK for
now.
I also added a good test-case for this, the PhysicsGroup EXD. It has a
lot of rows, and some packed booleans thrown in. The columns also have
out-of-order column definitions (as in, their offsets don't increase in
order.)
