Collect data from the "other" tree for the treewalk functions.

This enables us to log all relevant information that were used
to decide on sync activity.
Change data type for fileId to QByteArray.
Use QTimer as object member rather than pointer based.

Avoid crashes if timer is zero.
Safe use of c_strdup
Fix include path
Add a duration and the repsonse timestamp to the jobs.
Add a stopwatch utility class with lap times.

Allows to meassure the duration of something that started at a
point of time, with some small convenience methods.
Add a class to write a machine readable sync log file.
Add data to store interesting info from the sync run (other tree)
Store the request duration and timestamp to final item
Use a stopwatch to meassure the time consumed.
Log the processed items to a logfile.
Remove unused variable.