We want to check for new messages at the end of the loop, when all
other events should have happenned.
Handle the two supported messages there : tag info request and tag
programming command.
The timing might need some testing, hopefully it is short enough.
Remove the overide of the tag value used for testing.
We don't plan yet on playing effects when a tag leaves, so avoid
playing the effects twice and only do so when arriving.
Introduce the Speaker class to play audio from the SD card when detecting
tags.
The only audio supported is WAV.
Audio playback is handled via interrupts, so it might try to read from the
SD card at the same time as the LCD class is trying to read new frames.
Update the LCD animation code to temporarily disable audio interrupts while
reading from the SD card.
Add support for the LCD and using it for displaying animations.
Animations are automatically played if available for the ID of the
detected tag.
The code should support adding other kind of animations, for tags being
removed or for other UI interactions for example.
Implement a set of functions to create messages following the protocols
defined in the README for communication.
Handle HID, which is used to communicate with the interactive application.
Update README with details on the message structures.
Add a new class to handle the RFID module and associated data
in order to track active tags.
Update main with RFID initialization and a minimal usage to
check it is working as expected.
pinMode most of what could be useful in the main and put modules
LOW to minimize power draw before the regulator is ON.
Add the skeleton for the setup, main loop and battery level checking.
