Use model-offset in IfcGeom::Kernel and add model-rotation

src/serializers/GeometrySerializer.h

@@ -55,13 +55,7 @@ public:
     };
 
     SerializerSettings()
-        : precision(DEFAULT_PRECISION)
-    {
-        memset(offset, 0, sizeof(offset));
-    }
-
-    /// Optional offset that is applied to serialized objects, (0,0,0) by default.
-    double offset[3];
+        : precision(DEFAULT_PRECISION) { }
 
     /// Sets the precision used to format floating-point values, 15 by default.
     /// Use a negative value to use the system's default precision (should be 6 typically).