Add option to get Sound Level in decibels (dB)

[microbit-carlos]

CODAL has the option choose between 8-bit and dB for the LevelDetector. We had a couple of requests and it's already built in CODAL, so it'd be good to have it in the next beta.

API Options:

• Adding an argument to microphone.sound_level(), possibly microphone.sound_level(db=True)?
• Creating a new function like microphone.sound_level_db()
• Change units via different method, e.g. microphone.set_sound_level_unit(microphone.SOUND_LEVEL_DB)
  • This would be my least preferred option

[dpgeorge]

My preference would be microphone.sound_level_db(). It's simple. And it makes it very clear what the units are.

[microbit-carlos]

Agreed:

• docs: Add microphone.sound_level_db() function. bbcmicrobit/micropython#803

[dpgeorge]

See #221 for an implementation.

[dpgeorge]

Implemented in e876dca