BUG: Fix ImageToTubeRigidMetric angle computation.

Booooooo-ya!!!

Change-Id: Id02db587aa236cb62be71389fd2d52e9d9550115
ENH: Reg Tuner: Plot metric inverse.

So a semi-log-y plot will zoom in on the convergence.

Change-Id: Ie80a65d38d16e980709438367a941bf0116d0f8a
ENH: Reg Tuner: Export video frames.

Change-Id: Ia79a9519f030304dc333cc1f15bddc2ca3a319be