Replaced the 'postProcess' argument to the 'write' and 'execute'
functions with the single static member 'postProcess' in the
functionObject base-class.
the equivalent functionality is provided by the writeRegisteredObject
functionObject in a MUCH simpler, easier and extensible manner.
functionObject: Removed the now redundant 'timeSet' function.
This changes simplifies the specification of functionObjects in
controlDict and is consistent with the 'libs' option in controlDict to
load special solver libraries.
Support for the old 'functionObjectLibs' name is supported for backward compatibility.