ENH: multiple surfaces, self-intersection in surfaceFeatureExtract (issue #450)

- If the dictionary is named 'surfaces', a 'surfaces' entry is mandatory.
  This is a list of wordRe, which is used to load multiple surfaces from
  constant/triSurface directory.

- Other dictionaries may contain a 'surfaces' entry.
  In which case the behaviour is as above (loading multiple surfaces).
  The dictionary name will *NOT* be taken as a surface name itself.

- Regardless of how the surfaces are loaded or features extracted,
  an additional selfIntersection test may be used.

  Eg,

    surfaces
    {
        extractionMethod    extractFromSurface;

        surfaces            (surface1.stl surface2.nas);

        // Generate features from self-intersect
        selfIntersection    true;

        // Base output name (optiona)
        output              surfaces;

        // Tolerance for self-intersect
        planarTolerance     1e-3;

        extractFromSurfaceCoeffs
        {
            includedAngle   120;

            // Do not mark region edges
            geometricTestOnly       yes;
        }
    }

applications/utilities/surface/surfaceFeatureExtract/extractionMethod/surfaceFeaturesExtraction.C

@@ -0,0 +1,92 @@
+/*---------------------------------------------------------------------------*\
+  =========                 |
+  \\      /  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/>.
+
+\*---------------------------------------------------------------------------*/
+
+#include "surfaceFeaturesExtraction.H"
+#include "dictionary.H"
+#include "ListOps.H"
+#include "error.H"
+#include "addToRunTimeSelectionTable.H"
+
+// * * * * * * * * * * * * * * Static Data Members * * * * * * * * * * * * * //
+
+namespace Foam
+{
+namespace surfaceFeaturesExtraction
+{
+    defineTypeName(method);
+    defineRunTimeSelectionTable
+    (
+        method,
+        dictionary
+    );
+}
+}
+
+
+// * * * * * * * * * * * * * * * * Constructors  * * * * * * * * * * * * * * //
+
+Foam::surfaceFeaturesExtraction::method::method()
+:
+    includedAngle_(0),
+    geometricTestOnly_(Switch::NO)
+{}
+
+
+// * * * * * * * * * * * * * * * * Destructor * * * * * * * * * * * * * * * //
+
+Foam::surfaceFeaturesExtraction::method::~method()
+{}
+
+
+// * * * * * * * * * * * * * * * Member Functions  * * * * * * * * * * * * * //
+
+Foam::autoPtr<Foam::surfaceFeaturesExtraction::method>
+Foam::surfaceFeaturesExtraction::method::New
+(
+    const dictionary& dict
+)
+{
+    const word methodName = dict.lookup("extractionMethod");
+
+    dictionaryConstructorTable::iterator cstrIter =
+        dictionaryConstructorTablePtr_->find(methodName);
+
+    if (cstrIter == dictionaryConstructorTablePtr_->end())
+    {
+        FatalIOErrorInFunction
+        (
+            dict
+        )   << "Unknown extractionMethod "
+            << methodName << nl << nl
+            << "Valid extraction methods: :" << nl
+            << flatOutput(dictionaryConstructorTablePtr_->sortedToc())
+            << exit(FatalIOError);
+    }
+
+    return autoPtr<method>(cstrIter()(dict));
+}
+
+
+// ************************************************************************* //