Fixing the issues with {dual,quad}_flip in VTK-6.

VTK-6 algorithms only seem to work with SetInputConnection() rather
than SetInput().  These fixes may also be backwards-compatible with
VTK-5, need to check.

Refs #3544.
Fixing/regolding the flip_quad test.

There were a lot of issues with this test, but it now works with VTK-6
and produces a 4-fold symmetic image, which was the original intention
of the test.

Refs #3544.