bthidd(8) now was integrated with vkbd(4) and supports
multiple keyboards via vkbd(4)/kbdmux(4).
The code was tested with Apple Bluetooth keyboard and
SE k700i cell phone (remote control feature).
MFC after: 1 month
Note: bthidd(8) is still not complete. Need to commit kernel
support (a-la Linux /dev/input) to feed HID events into kernel.
Also need to write bthidd(8) and bthidd.conf(5) man pages.