ENH: ignore -noFunctionObjects option when disabled

- With argList::noFunctionObjects() we use the logic added in
  4b933332 (issue #352)

  By removing the '-noFunctionObjects' option, we automatically
  suppress the creation of function-objects via Time (with argList
  as a parameter).
  There is generally no need in these cases for an additional

      runTime.functionObjects().off()  statement

  Use the argList::noFunctionObjects() for more direct configuration
  and reduce unnecessary clutter in the -help information.

  In previous versions, the -noFunctionObjects would have been redundant
  anyhow, so we can also just ignore it now instead.