added missing Lf7 Signals: 20, 50, 80
added missing german Lf6 signals: 20, 50, 80
added Zs3v 70-160
minor corrections of some Lf6 and Lf7 proposed by ubahnverleih

- make corners rounded like in the existing Lf 7 icons (suggested by
  rurseekatze)
- remove little gap between the black outline and image boundings
  (suggested by rurseekatze)
improve Zs3 icons from ubahnverleih

- The corners are not rounded like in the existing Lf 7 icons
  (rurseekatze)
- There is a little gap between the black outline and the image
  boundings (rurseekatze)
Merge branch 'ubahnverleih-master' (adding missing Lf6, Lf7, Zs3, Zs3v)