ENH: ignore -noFunctionObjects option when disabled

- With argList::noFunctionObjects() we use the logic added in
  4b93333292 (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.

applications/solvers/basic/potentialFoam/overPotentialFoam/overPotentialFoam.C

@@ -125,7 +125,7 @@ int main(int argc, char *argv[])
     argList::addBoolOption
     (
         "withFunctionObjects",
-        "execute functionObjects"
+        "Execute functionObjects"
     );
 
     #include "setRootCase.H"

applications/solvers/basic/potentialFoam/potentialFoam.C

@@ -122,7 +122,7 @@ int main(int argc, char *argv[])
     argList::addBoolOption
     (
         "withFunctionObjects",
-        "execute functionObjects"
+        "Execute functionObjects"
     );
 
     #include "addCheckCaseOptions.H"