message: add hasColor to ColorMap
diff: @@ -11,6 +11,10 @@ export class ColorMap {
  private static get maxIndex(): number { return 0xffff; }
  private static scratchColorDef = new ColorDef();
  + public hasColor(color: number): boolean {
  + return undefined !== this._dict.get(color);
  + }
  +
  public getIndex(color: number): number {
  const found = this._dict.get(color);
  if (undefined !== found)
  