InstancingMesh: Added setColorAt method to type defintion

src/objects/InstancedMesh.d.ts

@@ -4,6 +4,7 @@ import { Material } from './../materials/Material';
 import { BufferAttribute } from './../core/BufferAttribute';
 import { Mesh } from './Mesh';
 import { Matrix4 } from './../math/Matrix4';
+import { Color } from './../math/Color';
 
 export class InstancedMesh <
 	TGeometry extends Geometry | BufferGeometry = Geometry | BufferGeometry,
@@ -22,7 +23,6 @@ export class InstancedMesh <
 
 	getMatrixAt( index: number, matrix: Matrix4 ): void;
 	setMatrixAt( index: number, matrix: Matrix4 ): void;
-
-
+	setColorAt( index: number, color: Color ): void;
 
 }