upgrade to DSMR5.1 especially powerpeak support

[jellevervloessem]

Extension of the P1meter:

• upgrade to DSMR5.1
  • eMUC 1.7.1 and powerpeak support for Belgian Meters
    • process 15min powerpeaks
    • process maximum monthly powerpeak
    • process average monthly powerpeak /12 months
    • send the 12 values as JSON over MQTT.

Lost of commits are included because of issues with forks/branches and cleanup afterwards...

[daniel-jong]

Thanks for the PR, looks good!

I think the following points are blocking

• Inversion of the Day and Night tariffs. Even if the current setup is incorrect users might depend on its. So I'll try to work on a way to offer old and new behaviour with some setting. This is something I could add in a follow up commit on this PR, but needs some time to prep.
• The Gasmeter's equipment id's. This also something I could work on after merging this back.

I just noticed that I have completely missed out on https://github.com/daniel-jong/esp8266_p1meter/pull/21/ that contains logic for both issues and should be able to merge that logic into these changes with not to much effort. Great!