Add inverse val for Symmetry trait
Add spec for Identity inverse
Add spec for MirrorRows inverse
Add spec for MirrorColumns inverse
Add spec for RotateBy180Degrees inverse
Add spec for MirrorDiagonal inverse
Add spec for MirrorAntidiagonal inverse
Drop debug printlns from spec
Add spec for RotateRightBy90Degrees inverse
Add spec for RotateRightBy270Degrees inverse