ENH: enhancements to behaviour of token

- improved memory alignment reduces overhead for Int32 compilation

- added move/swap semantics

- made the type() readonly in favour of setVariant() to allow change
  of variant within a particular storage representation.
  Eg, STRING -> VERBATIMSTRING.

applications/test/token/Make/files

@@ -0,0 +1,3 @@
+Test-token.C
+
+EXE = $(FOAM_USER_APPBIN)/Test-token

applications/test/token/Make/options

@@ -0,0 +1 @@
+/* EXE_INC = */

applications/test/token/Test-token.C

@@ -0,0 +1,75 @@
+/*---------------------------------------------------------------------------*\
+  =========                 |
+  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
+   \\    /   O peration     |
+    \\  /    A nd           | Copyright (C) 2017 OpenCFD Ltd.
+     \\/     M anipulation  |
+-------------------------------------------------------------------------------
+License
+    This file is part of OpenFOAM.
+
+    OpenFOAM is free software: you can redistribute it and/or modify it
+    under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    OpenFOAM is distributed in the hope that it will be useful, but WITHOUT
+    ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+    FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+    for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with OpenFOAM.  If not, see <http://www.gnu.org/licenses/>.
+
+Description
+    Test token construct assign etc.
+\*---------------------------------------------------------------------------*/
+
+#include "argList.H"
+#include "IOobject.H"
+#include "IOstreams.H"
+#include "IFstream.H"
+#include "StringStream.H"
+#include "cpuTime.H"
+#include "DynamicList.H"
+
+using namespace Foam;
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+//  Main program:
+
+int main(int argc, char *argv[])
+{
+    argList::noBanner();
+    argList::noParallel();
+
+    argList args(argc, argv, false, true);
+
+    token tok1;
+    Info<< "construct null: " << tok1.info() << endl;
+
+    tok1 = double(3.14159);
+    Info<< "assign double: " << tok1.info() << endl;
+
+    token tok2(tok1);
+    Info<< "copy construct: " << tok2.info() << endl;
+
+    tok1 = word("this-word");
+    Info<< "assign word: " << tok1.info() << endl;
+
+    token tok3(tok1);
+    Info<< "copy construct: " << tok3.info() << endl;
+    Info<< "orig: " << tok1.info() << endl;
+
+    token tok4(std::move(tok1));
+    Info<< "move construct: " << tok4.info() << endl;
+    Info<< "orig: " << tok1.info() << endl;
+
+    tok3 = tok4;
+    Info<< "assign token: " << tok3.info() << endl;
+    Info<< "orig: " << tok4.info() << endl;
+
+    return 0;
+}
+
+// ************************************************************************* //