The function arguments were reviewed to add missing 'const' keywords,
and some classes were modified more deeply to make some pointer class
variables constant.
Like in the other modules, we get rid of the old use of "access point".
This has user-visible changes, especially in the configuration (the name
of a few options has been changed).
The first field of the Aggregator's CSV output files is now an unsigned
integer that announces the version of the CSV format used. Current
version is 1 and the subsequent fields are not modified, so that an
aggregation file generated with a previous version can still be used by
adding "1;" at the beginning of each line.
The Positioner has been adapted to handle this new format.