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Bugfix #6847: Previous fix for "spikes" when using booleans caused creation
of faces with only two unique vertices ("eekadoodles"). This patch cleans up
the test for triangles with near-colinear vertices so PHANTOM faces can be
used again, and also adds a hack for now which removes any eekadoodle faces.
I haven't figured out yet exactly how the faces are being created; if I can
do so and fix it the hack will be removed.