Hotfix v0.09.X: EigenStepper can run into infinite loop

Closes #580 (closed) and #582 (closed)

This is the hot fix for release 0.09.X concerning the infinite loops. It does not fix the underlying problem, which will be dealt with on top of release 0.10.00, that requires however a change of Surface::intersect, ConstrainedStep and dropping of anyDirection. A final solution is prepared on origin/619-implementation-of-refactored-navigator

The fix in the EigenStepper is rather simple:

• it checks for a loop to occur (by checking the step number), and if something like this occurs, the stepper falls back to a small step size and continues. Once the navigation is caught again, it can go back to normal navigation.