- added clear() method to functionObjectList. It also gets called by ~Time().
This should destroy function objects before anything else gets
destroyed (eg, objectRegistry).
- This was originally plan 'B', but it is actually probably more efficient
than using PtrDictionary anyhow.
- straightened out the return value logic, but it wasn't being used anywhere
anyhow.
- new 'updated_' data member avoids inadvertent execution in the read()
method when execution is turned off.
