send invalid data as pseud-packages instead of plainly printing it

this allows aggregating invalid data (of which typically only the first
and/or last bytes matter).

this patch only changes the format of reporting, and does not include
said output optimizations (in fact, it drops the output of invalid data
completely).
output invalid data in aggregated form

successive messags of invalid frames are aggregated, and output at the
latest possible time (before something else is printed), possibly in
truncated form.
dissect the remaining unknown fields

of those, only timestamps are parsed into something usable. extensions
and reserved packages could be parsed a little further, but only to a
meaningless 32bit value.