ENH: improved infrastructure for writing VTK content

Note: classes are prefixed with 'foamVtk' instead of 'vtk' to avoid potential
conflicts with VTK itself.

foamVtkCore
~~~~~~~~~~~
- General very low-level functionality.

foamVtkPTraits
~~~~~~~~~~~~~~
- Traits type of functionality for VTK

foamVtkOutputOptions
~~~~~~~~~~~~~~~~~~~~
- The various format output options as a class that can be passed to
  formatters etc.

foamVtkCells
~~~~~~~~~~~~
- Intended for unifying vtkTopo and PV-Reader code in the future.
- Handles polyhedron decompose internally etc

foamVtkOutput, foamVtkFormatter
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
- Output helpers.
- Selector for individual formatters.
  Currently write all scalar data a 'float' (not 'double'). Can
  revisit this in the future.

src/fileFormats/vtk/format/foamVtkAsciiFormatter.C

@@ -0,0 +1,136 @@
+/*---------------------------------------------------------------------------*\
+  =========                 |
+  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
+   \\    /   O peration     |
+    \\  /    A nd           | Copyright (C) 2016 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/>.
+
+\*---------------------------------------------------------------------------*/
+
+#include "foamVtkAsciiFormatter.H"
+
+// * * * * * * * * * * * * * * Static Data Members * * * * * * * * * * * * * //
+
+const char* Foam::foamVtkAsciiFormatter::name_ = "ascii";
+
+
+// * * * * * * * * * * * * * Private Member Functions  * * * * * * * * * * * //
+
+inline void Foam::foamVtkAsciiFormatter::next()
+{
+    if (pos_ == 6)
+    {
+        os()<< '\n';
+        pos_ = 0;
+    }
+    else if (pos_)
+    {
+        os()<< ' ';
+    }
+    ++pos_;
+}
+
+
+// * * * * * * * * * * * * * * * * Constructors  * * * * * * * * * * * * * * //
+
+Foam::foamVtkAsciiFormatter::foamVtkAsciiFormatter(std::ostream& os)
+:
+    foamVtkFormatter(os),
+    pos_(0)
+{}
+
+
+Foam::foamVtkAsciiFormatter::foamVtkAsciiFormatter
+(
+    std::ostream& os,
+    unsigned precision
+)
+:
+    foamVtkFormatter(os),
+    pos_(0)
+{
+    os.precision(precision);
+}
+
+
+// * * * * * * * * * * * * * * * * Destructor  * * * * * * * * * * * * * * * //
+
+Foam::foamVtkAsciiFormatter::~foamVtkAsciiFormatter()
+{
+    flush();
+}
+
+
+// * * * * * * * * * * * * * * Member Functions  * * * * * * * * * * * * * * //
+
+const char* Foam::foamVtkAsciiFormatter::name() const
+{
+    return name_;
+}
+
+
+const char* Foam::foamVtkAsciiFormatter::encoding() const
+{
+    return name_;
+}
+
+
+void Foam::foamVtkAsciiFormatter::writeSize(const uint64_t)
+{/*nop*/}
+
+
+void Foam::foamVtkAsciiFormatter::write(const uint8_t val)
+{
+    next();
+    os()<< int(val);
+}
+
+
+void Foam::foamVtkAsciiFormatter::write(const label val)
+{
+    next();
+    os()<< val;
+}
+
+
+void Foam::foamVtkAsciiFormatter::write(const float val)
+{
+    next();
+    os()<< val;
+}
+
+
+void Foam::foamVtkAsciiFormatter::write(const double val)
+{
+    next();
+    os()<< float(val);
+}
+
+
+void Foam::foamVtkAsciiFormatter::flush()
+{
+    if (pos_)
+    {
+        os()<< '\n';
+    }
+    pos_ = 0;
+}
+
+
+// ************************************************************************* //