Gas value calculations are not correct

[erkr]

I filed an issue in the Esphome libraries for this Mics-4514 chip. That code was derived from this example. Main issue with this library:

• the gas detection graph in the mics 4514 datasheet is double logarithmic, but the value calculations are using linear interpolations.
  In the issue referred, I added the correct math to calculate the gas values using the Mics 4514.

Additionally it is highly misleading that the library suggests to measure these individual gasses. Note that the sensor is not selective. misc 4514 just hosts two sensors that respond to a group of oxidative and reducing gasses. So just one of the detected gasses needs to be actual present for a readout for all gasses in that range. One can simply not tell which one.