Addition of DWD parser

[SgtSeppel]

I wrote a simple parser for the german DWD.

More information can be found here: https://support.rainmachine.com/hc/en-us/community/posts/360009706793-Parser-for-german-DWD-Deutscher-Wetterdienst-

[nicupavel]

Code looks good, I'll test on my side as soon as possible.