Fix recurring error T22510 "Invalid ImageAccessor: PixelTypes of Image and ImageAccessor are not equal".

Summary:
QmitkImageNavigatorView::UpdateStatusBar() and mitkDisplayInteractor::UpdateStatusBar() had the same problem.
Add an else if() case for SYMMETRICSECONDRANKTENSOR and DIFFUSIONTENSOR3D in UpdateStatusBar().
Detailed diagnostics output for mitk::PixelType::operator==.

Test Plan: In MitkWorkbench, load a *.dti and click on it anywhere in the stdMultiWidget.

Reviewers: O1 MITK Core, goch

Reviewed By: O1 MITK Core, goch

Subscribers: kislinsk, goch

Tags: MITK

Differential Revision: https://phabricator.mitk.org/D37