New source: Add support for Speyer through Gipsprojekt / ICS source

[DerDreschner]

As already thought in #3479, there are indeed other cities still using Gipsprojekt. Speyer is such an example that was requested in #3572. This pull request adds the necessary links and documentation (not only in English, but German as well).

Closes #3572

[perlchamp]

a little additional note:
the link of speyer is tricky, cause you have to use {%Y} TWICE !
https://www.stadtwerke-speyer.de/speyerGips/Gips?SessionMandant=Speyer&Anwendung=Abfuhrkalender&Methode=TermineAnzeigenICS&Mandant=Speyer&Abfuhrkalender=Speyer{%Y}&Bezirk_ID=17&Jahr={%Y}

[DerDreschner]

Yeah, that's why I changed the documentation to check for any year:

Check the URL for any year. In the case of Speyer, it is the case in the Abfuhrkalender and Jahr argument. Replace it with {%Y} as seen in the example configuration.

It's different to Heidelberg and - honestly - quite redundant. But... It is, what it is.

[5ila5]

I don't like Replace the url in the example configuration with the copied link. anymore, as it now also appears in the GUI configuration where there is no example. I remove it every time I touch an ICS source containing this sentence.

I'd prefer something like: "Use this URL as the url parameter"