Improve German localisation (DE)

[XDA-Bam]

This brings the German localisation from about 30% to about 80% complete.

Some remarks:

• This PR is untested since I currently don't have the build environment set up and don't have a spare NCP install to test on. I hope it's not too much work for you to check this in your test env.
• For some menu points in the panel, there are no translastions at all (no corresponding folders, no ES, PT or other translation files). One example is ncp-community. Those are also missing in this PR. I'm not sure if this is a simple "add folder, put in de.json" thing, or if other code changes are required to add these translations. Please let me know.
• I have seen some garbled Umlauts in files, while others were OK. I de-garbled those I could find and hope they work correctly now.