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/extractFromSurface.C

@@ -0,0 +1,102 @@
+/*---------------------------------------------------------------------------*\
+  =========                 |
+  \\      /  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 "extractFromSurface.H"
+#include "addToRunTimeSelectionTable.H"
+
+#include "triSurface.H"
+#include "triSurfaceSearch.H"
+#include "scalarField.H"
+#include "edgeIntersections.H"
+
+
+// * * * * * * * * * * * * * * Static Data Members * * * * * * * * * * * * * //
+
+namespace Foam
+{
+namespace surfaceFeaturesExtraction
+{
+    addNamedToRunTimeSelectionTable
+    (
+        method,
+        extractFromSurface,
+        dictionary,
+        extractFromSurface
+    );
+}
+}
+
+
+// * * * * * * * * * * * * * * * * Constructors  * * * * * * * * * * * * * * //
+
+Foam::surfaceFeaturesExtraction::extractFromSurface::extractFromSurface
+(
+    const dictionary& dict
+)
+:
+    method()
+{
+    const dictionary& coeffDict = dict.subDict("extractFromSurfaceCoeffs");
+
+    coeffDict.lookup("includedAngle") >> includedAngle_;
+    coeffDict.readIfPresent("geometricTestOnly", geometricTestOnly_);
+}
+
+
+// * * * * * * * * * * * * * * * * Destructor * * * * * * * * * * * * * * * //
+
+Foam::surfaceFeaturesExtraction::extractFromSurface::~extractFromSurface()
+{}
+
+
+// * * * * * * * * * * * * * * * Member Functions  * * * * * * * * * * * * * //
+
+
+Foam::autoPtr<Foam::surfaceFeatures>
+Foam::surfaceFeaturesExtraction::extractFromSurface::features
+(
+    const triSurface& surf
+) const
+{
+    Info<< nl << "Constructing feature set from included angle "
+        << includedAngle() << nl
+        << "Selecting edges based purely on geometric tests: "
+        << geometricTestOnly().asText() << endl;
+
+    return autoPtr<surfaceFeatures>
+    (
+        new surfaceFeatures
+        (
+            surf,
+            includedAngle(),
+            0,  // minLen
+            0,  // minElems
+            geometricTestOnly()
+        )
+    );
+}
+
+
+// ************************************************************************* //