Evaluate at point efficiently

This changes `EvaluateAtPoint` -- and hence `InterpolateToPoint` and `Translate` -- to be able to handle `Waveform`s in rotating frames.  There is almost no more reason to ever transform to the inertial frame, and staying in a rotating frame should generally be better numerically.  The one remaining exception is that the `Translate` function returns the `Waveform` in the inertial frame.  This is because of a subtlety I haven't yet worked out involved in preserving the rotating frame, having to do with the nonlinear relationship between translations being direction-dependent time offsets and time-dependent directions in a rotating frame.