device interface

A new interface has been added to dbus2vdr. From the README:

Interface "device"

• get current primary device
  vdr-dbus-send.sh /Devices device.GetPrimary

• request switch to primary device
  vdr-dbus-send.sh /Devices device.RequestPrimary int32:index

• list devices
  vdr-dbus-send.sh /Devices device.List

  The returned array contains the device index, number, a boolean value "hasDecoder",
  a boolean value "isPrimary" and the name of the device.