* allow to use --log-in <infile> and --log-out <outfile> in the same time
* add --log-io <file> to log stdout and stdin to the one log file
* introduce a new timing file format with entry type identifirs
I <delay> <size> : info about input stream
O <delay> <size> : info about output stream
in the next commits it's possible to add 'S' for signals and 'H' for
extra (header) information.
* the new file format is optional and enabled only if multiple streams
logging is requested.