Add QCanTraceFile class for reading/writing CAN log files

CAN bus analysis is usually done with CAN monitors that dump data into log files. Later this log files can be inspected by hand or with data visualisation tools.

Therefore, it would be nice to read/write different log file formats directly with QVector<QCanBusFrame>

The actual decoding logic could be done by

QCanBusFrame::{from|to}String(StringFormat format);