This had been used in functionObjects:
Info(log)<< "messages" << data << ....
in which it is not at all clear what the "log" argument does whereas
if (log) Info<< "messages" << data << ....
is totally clear and more efficient.
Previous behavior which may be useful for moving-mesh cases can be
selected using the optional entry:
writeTotalArea yes;
The initial total area is written in the log and data file header e.g.:
# Source : faceZone f0
# Faces : 8
# Area : 1.063860e-02
