* Remove need for separate `&cp` behavior, but keep it for now for backward compat. * Refactor sensor inc/dec as well.
Deprecate `USAGE_KEYPAD` and replace with `HID_USAGE_KEY`. Deprecate `USAGE_CONSUMER` and replace with `HID_USAGE_CONSUMER`. Closes #217.
Developed from specification: https://usb.org/sites/default/files/hut1_21.pdf Closes #217. Prerequisite of #21.