fullread has been changed, so get_event too, and the callers also
for the moment the callers crash, enb.c will be a bit more clever,
the others to see...
as special events.
If we store all received events to a file, this dump is now
self-contained. Helps to analyze traces.
Some functions have also been factorized in the process, too much
duplication.
(Also tracer/Makefile was forgotten in previous commit, included
in this one...)