ENH: consolidate handling of mandatory/optional command arguments

- for some special cases we wish to mark command-line arguments as
  being optional, in order to do our own treatment. For example,
  when an arbitrary number of arguments should be allowed.

  Now tag this situation with argList::noMandatoryArgs().
  The argList::argsMandatory() query can then be used in any further
  logic, including the standard default argument checking.

- with the new default check, can consolidate the special-purpose

      "setRootCaseNonMandatoryArgs.H"

  into the regular

      "setRootCase.H"

- revert to a simple "setRootCase.H" and move all the listing related
  bits to a "setRootCaseLists.H" file. This leaves the information
  available for solvers, or whoever else wishes, without being
  introduced everywhere.

- add include guards and scoping to the listing files and rename to
  something less generic.

     listOptions.H -> setRootCaseListOptions.H
     listOutput.H  -> setRootCaseListOutput.H

applications/solvers/electromagnetics/electrostaticFoam/electrostaticFoam.C

@@ -44,8 +44,7 @@ int main(int argc, char *argv[])
     );
 
     #include "addCheckCaseOptions.H"
-    #include "setRootCase.H"
-
+    #include "setRootCaseLists.H"
     #include "createTime.H"
     #include "createMesh.H"
     #include "createFields.H"

applications/solvers/electromagnetics/magneticFoam/magneticFoam.C

@@ -71,7 +71,7 @@ int main(int argc, char *argv[])
     );
 
     #include "addCheckCaseOptions.H"
-    #include "setRootCase.H"
+    #include "setRootCaseLists.H"
     #include "createTime.H"
     #include "createMesh.H"
 

applications/solvers/electromagnetics/mhdFoam/mhdFoam.C

@@ -68,7 +68,7 @@ int main(int argc, char *argv[])
     #include "postProcess.H"
 
     #include "addCheckCaseOptions.H"
-    #include "setRootCase.H"
+    #include "setRootCaseLists.H"
     #include "createTime.H"
     #include "createMesh.H"
     #include "createControl.H"