ENH: adding hook adjustTimeStep to function objects. The hook is called in

Time::adjustDeltaT(). It allows function objects to manipulate the time step to
    dump at adjustable times. The following options are available for output in
    function objects: timeStep, outputTime, adjustableTime, runTime, clockTime
    and cpuTime.

src/OpenFOAM/db/functionObjects/functionObject/functionObject.C

@@ -126,6 +126,12 @@ bool Foam::functionObject::timeSet()
 }
 
 
+bool Foam::functionObject::adjustTimeStep()
+{
+    return false;
+}
+
+
 Foam::autoPtr<Foam::functionObject> Foam::functionObject::iNew::operator()
 (
     const word& name,