New weather module: support for missing config entries

[vincep5]

In the existing weatherforecast.js, we have the ability to fade the forecast (config setting) fade and fadePoint. Is it possible to carry this over to the weather module when we display a forecast ? @fewieden

scale and maxNumberOfDays and retryDelay are other missing ones.

[MichMich]

There are a few other things to address. Maybe its a good idea to add a wiki page with a todo list so we can add stuff on a list. Or should we make separate issues with [Weather Module] at the start if the title?

[vincep5]

Wiki page would be good. Then we figure what is needed