For now this module serves as a helper for printing diagnostic
dictionary values. The new API (diagnostic_display) takes a
Dbus iterator which has been entered into a dictionary and
prints out each key and value. A mapping struct was defined
which maps keys to types and units. For simple cases the mapping
will consist of a dbus type character and a units string,
e.g. dBm, Kbit/s etc. For more complex printing which requires
processing the value the 'units' void* cant be set to a
function which can be custom written to handle the value.
