Copy head@r302406 to stable/11 as part of the 11.0-RELEASE cycle.
Prune svn:mergeinfo from the new branch, as nothing has been merged
here.

Additional commits post-branch will follow.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

Bluetooth SIG is being difficult and keep moving specification
documents away from being public accessible. Replace link to
the Bluetooth specification document with the document name.

Pointed out by: SoftLover < slserg at uic dot tula dot ru >
MFC after: 3 days

Start integrating Bluetooth into rc.d system.

Introduce /etc/rc.d/bluetooth script to start/stop Bluetooth devices. It
will be called from devd(8) in response to device arrival/departure events.
It is also possible to call it by hand to start/stop particular device
without unplugging it.

Introduce generic way to set configuration parameters for Bluetooth devices.
By default /etc/rc.d/bluetooth script has hardwired defaults compatible
with old rc.bluetooth from /usr/share/netgraph/bluetooth/examples. These
can be overridden using /etc/defaults/bluetooth.device.conf file (system
wide defaults). Finally, there could be another device specific override
file located in /etc/bluetooth/$device.conf (where $device is ubt0, btccc0
etc.)

The list of configuration parameters and their meaning described in the
/etc/defaults/bluetooth.device.conf file. Even though Bluetooth device
configuration files are not shell scripts, they must follow basic sh(1) syntax.

The bluetooth.device.conf(5) and handbook update will follow shortly.

Inspired by: Panagiotis Astithas ( past at ebs dot gr )
Reviewed by: brooks, yar
MFC after: 1 week