Added polling flag to MultiTrellis::read

[ukmaker]

Theread()method in MultiTrellis does not currently support the polling flag. This results in unnecessary bus activity which injects noise in to the PSU for audio applications.

This PR adds the flag, default to true if not supplied so as not to change the API for existing apps.

This PR also duplicates the logic if (polling) count = count + 2; which exists in the NeoTrellis::read(0 method. However I have no idea what this actually does (there is no comment explaining it). But it works for me :-)

[ladyada]

hiya! thanks so much for submitting a PR! we can review & merge PRs once they have passed continuous integration (CI). that means that code compiles cleanly for all tested platforms, is clang formatted so we maintain the same text formatting for all new code, and is doxygen documented.
if your code isnt passing, check the CI output (click on the red X next to the PR to scroll through the log and find where the error is

here is a tutorial on doxygen: https://learn.adafruit.com/the-well-automated-arduino-library/doxygen

and clang-format: https://learn.adafruit.com/the-well-automated-arduino-library/formatting-with-clang-format

and overall how to contribute PRs to libraries: https://learn.adafruit.com/contribute-to-arduino-with-git-and-github

once you get that green checkmark that indicates CI has passed, please comment reply to this post so we know its time for another review (we may not get notified on CI pass and miss that its time to look!)

[ukmaker]

I hope this is useful! Not having to poll also frees up valuable CPU cycles for other things

[ukmaker]

Hi there. Will these be merged?