New via-ferrata grading (Hüsler)

Salut!

By popular demand we replaced the via-ferrata scale from French scale to "K" scale used by SAC-CAS  (aka Hüsler scale) see here.

The mapping from the old to the new scale is pretty direct

L/F -> K1
WS/PD -> K2
ZS/AD -> K3
S/D -> K4
SS/TD - > K5
ED(didn't exist) -> K6

You can see the result here

The documentation pages are also updated. Unfortunately there is no Italian translation on the SAC website, not sure why?

Please let me know if everything is correct! If it's not correct we can always modify it or change back how it was before.

Also, if you know a good comparison between scales of different countries, to would like to add that in the documentation.

EDIT Changed it so "K" scale will be used for all interface languages except Italian and French, in which case old scale will be used. And on the page of the report it will always show both scales 

Thanks to georgb and kopfsalat for the help!