Adjusts maxNumberOfDays depending on the endpoint

[oemel09]

Fixes #2018

Now the cnt is set depending on the endpoint

• for 'forecast/daily' the maxNumberOfDays is used directly
• for 'forcast' maxNumberOfDay is adjusted. The maximum here is 5 days

The documentation for this module need to be adjusted as well:
https://docs.magicmirror.builders/modules/weatherforecast.html#configuration-options

If a free API token is used this description fits the maxNumberOfDays config:
Possible values: 1 - 5
Default value: 5 (5 days)

Else the config description remains the same

[oemel09]

Which to use, floor or ceil, may even depend on how the API works exactly...
Not sure if that check is needed anyway, but what I'm trying to do is to only get a full day from the API.
Because once you get the forecast till noon, it could still be cooler in the evening on that day, so the forecast would display some wrong minimal temperature for that day, because it doesn't have the data for the evening yet.