Factorize event ID checkingn into separate method
Statistics: add yet another number: errors_pixel_incomplete() gets
filled if the data stream contains incomplete pixel hits (<24bits).
This is checked by looking for the arrival of any TBM marker while
reading pixel data.
datapipes: check for DESER400 failures (ROC header 4XXH with
XX being 0xFF). For now we just display a CRITICAL message, but
do nothing. Maybe abort here?