New I2C sensors supported

[Didier B]

Thanks to the helpers for influxdb !

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About mysterious I2C info (temperature, atmospheric pressure) disappearing : 

• It occurs repetitively after a few hours ;
  
• Pipylot info (pitch, heel & heading) are not affected and remains available ;
  
• Stopping/starting OpenCPN doesn't allow to recover lost I2C info ;
  
• Neither re-starting signal K server ;
  
• Nor rebooting the Pi (after stopping OpenCPN) ;
  
• Only shutdown and power cut-off, followed by a complete cold restart of the Pi allows to get I2C info back.
  
• After a cold start I2C info is always present ;
  
• both I2C and Pipylot data are generated by the same (and only) GY91 module.
  

EDIT : next day, this evening, more of the same : after new I2C info disappearance, I could check once more that going through un-powering was required to recover.

• I then started to play with the GY91 module. When removing the GND wire from GPIO, after 7 to 10 seconds Pypilot info disappear, then 15 s later I2C info vanishes.
  
• When re-plugging this GND wire, everything comes back almost instantly (say less than one second).
  

Next test : after spontaneous disappearance of I2C info, I will try to unplug/replug this GND wire... almost waiting for it to happen !