Some improvements to the German template

Avoided unnecessary abbreviations, typography, included lf6/lf7 icons, removed some non-existing signals, provided some examples, common choice of gauges
Names of signal types should be written in lower case
Bugfix: Milestone API request failed when handling comma values
New translations added, existing translations updated
Added translators to authors list
Merge pull request #46 from bigbug21/master Improvements of German JOSM preset
Merge branch 'bigbug21-master'