standard IEEE1588-2018

We bring here a lot of changes to :
- make the implementation more complaiant with the standard
IEEE1588-2018.
  We introduce new structures for the time (TimeInterval, Relative
difference)
  Named used in structures are aligned to the standard, ...
  It is just a first step. More work is needed
- be able to use more than one protocol extension at the same time
  (configurations, structures, ...)
- add the concept of profile
- increase diagnostics by displaying also standard PTP servo
informations