Add SkLights class

include/core/SkPoint3.h

Index: include/core/SkPoint3.h
diff --git a/include/effects/SkPoint3.h b/include/core/SkPoint3.h
similarity index 90%
rename from include/effects/SkPoint3.h
rename to include/core/SkPoint3.h
index c086931c08feb8fe698a8aea876e9f24553f3e65..2d93b8e0a374feafbf5529c6d0e73b8895e2ea3e 100644
--- a/include/effects/SkPoint3.h
+++ b/include/core/SkPoint3.h
@@ -97,6 +97,22 @@ struct SK_API SkPoint3 {
         return v;
     }
 
+    /** Add v's coordinates to the point's
+    */
+    void operator+=(const SkPoint3& v) {
+        fX += v.fX;
+        fY += v.fY;
+        fZ += v.fZ;
+    }
+
+    /** Subtract v's coordinates from the point's
+    */
+    void operator-=(const SkPoint3& v) {
+        fX -= v.fX;
+        fY -= v.fY;
+        fZ -= v.fZ;
+    }
+
     /** Returns the dot product of a and b, treating them as 3D vectors
     */
     static SkScalar DotProduct(const SkPoint3& a, const SkPoint3& b) {