NOTES

Lessons learned during development:

UDEV RULES:

  udevadm info -q path -n /dev/hidraw0 will get you the syspath to the
  device (/devices/whatever)
  udevadm info -a -p /devices/whatever
  will walk the tree from that device up and show you various things,
  include the keys to match in the udev rule.  Note that sometimes the
  key is plural (SUBSYSTEMS) and sometimes it's not.  Read carefully.

  udevadm test /devices/whatever will show you what's getting done and
  why
  udevadm trigger will actually re-run the rules (as root).

  Note that we need two rules, one for the raw USB device (which
  prevents EACCESS libusb errors), and one for the actual HID device (hidraw0)