Volume animation

[gamblor21]

A new animation that takes MP3Decoder volume and adjusts the neopixels both in brightness and number of lit pixels. It could also consume any other object that has a member that reflects the current audio volume.

[jposada202020]

@kattni, this one is ready for review also. thanks

[kattni]

@gamblor21 Hey! We're taking a look at this now. You submitted it before we started using the reuse licensing. Please update the licensing along with any possible suggestions we may have regarding the code.

I would suggest running it through pre-commit to make sure it fits with our current standards.

[rhooper]

@gamblor21 This could use an example in the examples directory. I finally managed to make it sort of work after a bit of fiddling.
Type hints would also be great. See #83 for examples. Pin for type hints can be found in microcontroller.

I had this to test, though I never got it to play nicely as the speaker stuttered badly.

import board

from adafruit_macropad import MacroPad
from adafruit_led_animation.animation.volume import Volume
from audiomp3 import MP3Decoder
from audiopwmio import PWMAudioOut as AudioOut

macropad = MacroPad()
macropad._speaker_enable.switch_to_output(True)

# shutdown = digitalio.DigitalInOut(board.SPEAKER_ENABLE)
# shutdown.switch_to_output(True)

mp3 = open('slow.mp3', 'rb')
decoder = MP3Decoder(mp3)
audio = AudioOut(board.SPEAKER)
audio.play(decoder)
a = Volume(macropad.pixels, 0.01, (255, 0, 255), decoder)
while audio.playing:
    a.animate()

[gamblor21]

Just a note that I saw the comments and haven't forgotten about this PR. I hope to have some time soon that I can revisit and update things. Adding an example is a great idea and I can do that as well.

[FoamyGuy]

This same change was in #67 as well. I think it's easiest to just keep it from there and close this one to avoid any merge weirdness.

I added an example for the volume animation in a commit over in #67 as well, though I didn't realize there was one in a comment here at the time so it's a little different.

closing this one in favor of keeping #67