Add an adapter for IfcGeom::SurfaceStyle so that IfcGeomObjects (and most notably the Python wrapper) need not to be aware of boost::optional

Expose shading and rendering styles to the Python wrapper as well

src/ifcwrap/IfcPython.i

@@ -19,12 +19,30 @@
 
 %include "std_vector.i"
 %include "std_string.i"
+%include "exception.i"
+
+%typemap(out) const double* {
+	// This is only used for RGB colours, hence the size of 3
+	$result = PyTuple_New(3);
+	for (int i = 0; i < 3; ++i) {
+		PyTuple_SetItem($result, i, PyFloat_FromDouble($1[i]));
+	}
+}
+
+%exception {
+	try {
+		$action
+	} catch(std::runtime_error& e) {
+		SWIG_exception(SWIG_RuntimeError, e.what());
+	} catch(...) {
+		SWIG_exception(SWIG_RuntimeError, "An unknown error occurred");
+	}
+}
 
 %include "Interface.h"
 
 %module IfcImport %{
 	#include "Interface.h"
-	using namespace IfcGeom;
 	using namespace IfcGeomObjects;
 %}
 
@@ -37,6 +55,7 @@
 			faces = property(faces)
 			edges = property(edges)
 			normals = property(normals)
+			material_ids = property(material_ids)
 			materials = property(materials)
 		def __repr__(self): return "RepresentationTriangulation #%d"%self.id
     %}
@@ -84,7 +103,24 @@
     %}
 };
 
+%extend IfcGeomObjects::Material {
+	%pythoncode %{
+		if _newclass:
+			# Hide the getters with read-only property implementations
+			has_diffuse = property(hasDiffuse)
+			has_specular = property(hasSpecular)
+			has_transparency = property(hasTransparency)
+			has_specularity = property(hasSpecularity)
+			diffuse = property(diffuse)
+			specular = property(specular)
+			transparency = property(transparency)
+			specularity = property(specularity)
+		def __repr__(self): return "Material"
+    %}
+};
+
 namespace std {
 	%template(IntVector) vector<int>;
 	%template(FloatVector) vector<float>;
+	%template(MaterialVector) vector<IfcGeomObjects::Material>;
 };

src/ifcwrap/Interface.h

@@ -17,11 +17,6 @@
  *                                                                              *
  ********************************************************************************/
 
-namespace IfcGeom {
-	class SurfaceStyle {
-	};
-}
-
 namespace IfcGeomObjects {
 
 	const int WELD_VERTICES = 1;
@@ -33,6 +28,21 @@ namespace IfcGeomObjects {
 	const int FORCE_CCW_FACE_ORIENTATION = 7;
     const int DISABLE_OPENING_SUBTRACTIONS = 8;
 
+	class Material {
+	private:
+		void* style;
+	public:
+		bool hasDiffuse() const;
+		bool hasSpecular() const;
+		bool hasTransparency() const;
+		bool hasSpecularity() const;
+		const double* diffuse() const;
+		const double* specular() const;
+		double transparency() const;
+		double specularity() const;
+		const std::string name() const;
+	};
+
 	class IfcRepresentationTriangulation {
 	private:
 		int _id;
@@ -40,8 +50,8 @@ namespace IfcGeomObjects {
 		std::vector<int> _faces;
 		std::vector<int> _edges;
 		std::vector<float> _normals;
-		std::vector<int> _materials;
-		std::vector<const IfcGeom::SurfaceStyle*> _surface_styles;
+		std::vector<int> _material_ids;
+		std::vector<Material> _materials;
 
 		IfcRepresentationTriangulation();
 		IfcRepresentationTriangulation(const IfcRepresentationTriangulation&);
@@ -53,7 +63,8 @@ namespace IfcGeomObjects {
 		const std::vector<int>& faces() const;
 		const std::vector<int>& edges() const;
 		const std::vector<float>& normals() const;
-		const std::vector<int>& materials() const;
+		const std::vector<int>& material_ids() const;
+		const std::vector<Material>& materials() const;
 	};
 
 	class IfcRepresentationBrepData {