New fixed segment showing position of current view

Solves #539
Fixed version of #540 and #579
Works now for split windows and wrapped lines.
Merge branch 'develop' into feature/539-position-segment
Small fixes for new position segment

- use vim_funcs
- use a dictionary instead of a tuple for translation strings
More test cases for position segment
Merge pull request #750 from EinfachToll/feature/539-position-segment

New (fixed) segment showing position of current view