Fix the crosshair rotation zone

Summary:
The rotation zone is a clean cross only for image with a standard
spacing such as (1.0, 1.0, 1.0) or near. A bigger spacing reduces
the zone's width. A smaller spacing makes the zone bigger and farther,
which can make the rotation unusable.

Signed-off-by: Nil Goyette nil.goyette@imeka.ca

Merge branch 'T22573-RotationZone' of git://github.com/nilgoyette/MITK into T22573-rotation-interaction-zone-does-not-scale

Test Plan: Manual testing for very small spacings seems to work much better. There still might be issues for images only a couple of voxels across

Reviewers: O1 MITK Core, kislinsk

Reviewed By: O1 MITK Core, kislinsk

Maniphest Tasks: T22573

Differential Revision: https://phabricator.mitk.org/D52