Added feature of fixed sized PlanarCircle and PlanarDoubleEllipse.

Summary:
Signed-off-by: Ralf Floca <r.floca@dkfz-heidelberg.de>

Add fixed mode to QmitkMeasurementView

Signed-off-by: Ralf Floca <r.floca@dkfz-heidelberg.de>

Test Plan: Review and test in workbench.

Reviewers: O1 MITK Reviewer Group I, kalali

Reviewed By: O1 MITK Reviewer Group I, kalali

Maniphest Tasks: T27202

Differential Revision: https://phabricator.mitk.org/D262