Use raw values

[cod3gen]

May not be of interest, but the orginal setADC did not work good enough for me. Added setADCRaw which allows to use raw values, and included an async example of doing this like in ADS1X15.

[RobTillaart]

Thanks for the improvement,
Will look into it later, possibly after weekend as I am quite busy

[RobTillaart]

The build-CI broke so I took time to look and your PR raises serious questions.

• Q1: can you explain the goal you want to accomplish with the PR?
• Q2: the new variable _raw is never set, how should this work?
• Q3: the new variable _readADCRaw is set once in setADCRaw(), how should this work?
• Q4: the new example does not transfer the raw reading from the ADS1115 to the ACS712, how should this work?

Q1 is the most important, as that gives the rationale why you wrote this PR.

[cod3gen]

Apparently, my head was not included yesterday. I have issues using the callback function with setADC inside a class, but what i have done here will never update the value.