ENH: Initial integration of IHCantrabria wave functionality

- Wave models significantly restructured and refactored into a hierarchy of run-time selecatable models
- Gravity no longer hard-coded
- Ability to use any direction as the gravity direction
- Boundary conditions simplified and take reference to the wave model
  - removes a lot of code duplication and new code is ~30% faster
- Removed unused functions

Requires further testing
- Restart behaviour needs to be addressed

integration/OpenCFD/code/waveModel/waveAbsorptionModels/base/waveAbsorptionModel/waveAbsorptionModel.C

@@ -0,0 +1,80 @@
+/*---------------------------------------------------------------------------*\
+  =========                 |
+  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
+   \\    /   O peration     |
+    \\  /    A nd           | Copyright (C) 2016 OpenCFD Ltd.
+     \\/     M anipulation  | Copyright (C) 2015 IH-Cantabria
+-------------------------------------------------------------------------------
+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 "waveAbsorptionModel.H"
+
+// * * * * * * * * * * * * * * Static Data Members * * * * * * * * * * * * * //
+
+namespace Foam
+{
+namespace waveModels
+{
+    defineTypeNameAndDebug(waveAbsorptionModel, 0);
+}
+}
+
+
+// * * * * * * * * * * * * * * * * Constructors  * * * * * * * * * * * * * * //
+
+Foam::waveModels::waveAbsorptionModel::waveAbsorptionModel
+(
+    const dictionary& dict,
+    const fvMesh& mesh,
+    const polyPatch& patch,
+    const bool readFields
+)
+:
+    waveModel(dict, mesh, patch, false)
+{
+    if (readFields)
+    {
+        read();
+    }
+}
+
+
+// * * * * * * * * * * * * * * * * Destructor  * * * * * * * * * * * * * * * //
+
+Foam::waveModels::waveAbsorptionModel::~waveAbsorptionModel()
+{}
+
+
+// * * * * * * * * * * * * * * * Member Functions  * * * * * * * * * * * * * //
+
+bool Foam::waveModels::waveAbsorptionModel::read()
+{
+    if (waveModel::read())
+    {
+        // Note: always set to true
+        activeAbsorption_ = true;
+
+        return true;
+    }
+
+    return false;
+}
+
+
+// ************************************************************************* //

integration/OpenCFD/code/waveModel/waveAbsorptionModels/base/waveAbsorptionModel/waveAbsorptionModel.H

@@ -0,0 +1,95 @@
+/*---------------------------------------------------------------------------*\
+  =========                 |
+  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
+   \\    /   O peration     |
+    \\  /    A nd           | Copyright (C) 2016 OpenCFD Ltd.
+     \\/     M anipulation  | Copyright (C) 2015 IH-Cantabria
+-------------------------------------------------------------------------------
+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/>.
+
+Class
+    Foam::waveAbsorptionModel
+
+Description
+
+\*---------------------------------------------------------------------------*/
+
+#ifndef waveModels_waveAbsorptionModel_H
+#define waveModels_waveAbsorptionModel_H
+
+#include "waveModel.H"
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+namespace Foam
+{
+namespace waveModels
+{
+
+/*---------------------------------------------------------------------------*\
+                    Class waveAbsorptionModel Declaration
+\*---------------------------------------------------------------------------*/
+
+class waveAbsorptionModel
+:
+    public waveModel
+{
+protected:
+
+    // Protected Member Functions
+
+        //- Wave direction
+        virtual scalar direction() const
+        {
+            return -1;
+        }
+
+
+public:
+
+    //- Runtime type information
+    TypeName("waveAbsorptionModel");
+
+    //- Constructor
+    waveAbsorptionModel
+    (
+        const dictionary& dict,
+        const fvMesh& mesh,
+        const polyPatch& patch,
+        const bool readFields = true
+    );
+
+    //- Destructor
+    virtual ~waveAbsorptionModel();
+
+    // Public Member Functions
+
+        //- Read from dictionary
+        virtual bool read();
+};
+
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+} // End namespace waveModels
+} // End namespace Foam
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+#endif
+
+// ************************************************************************* //