TwistShift should be sorted out

[ZedThree]

trafficstars

It's currently in Mesh::Communicate, but maybe should be a parallel transform

[d7919]

If we were allowed to create multiple parallel transform instances then we can reuse the code inside the shifted metric -- either introducing an extra routine which just applies to the y-boundaries or just using the existing loops and changing which shiftZ routine is called.

[d7919]

Is this going to make v4.2 or will it be pushed back?

[ZedThree]

Pushed back