common optional SYSEX commands

[monteslu]

Thinking it would be cool if we kept some documentation around of SYSEX commands people are using. Things such as the codes for neopixel interaction in node-pixel or the accelerometers in playground-io.

No set in stone registry, just documentation on what's being used to help avoid collisions or give guidance on implementation for new hardware.

[soundanalogous]

there is a place to do that here: https://github.com/firmata/protocol/blob/master/feature-registry.md

If it's not in the registry, then it shouldn't be used in any public library. If there's a collision, it's the fault of the library author in that case for not getting it into the registry. (well which is sorta unfair since I didn't create the registry until a few months ago... but going forward that should be the practice).

[soundanalogous]

These types of hardware-specific features should also use the Extended ID (00H nnH nnH). For example we can add IDs for the accelerometers in playground-io, but they have to be the 3 byte variety.