message: WIP add textureMapping to DisplayParams
diff: | $Copyright: (c) 2018 Bentley Systems, Incorporated. All rights reserved. $
  *--------------------------------------------------------------------------------------------*/
  -import { GraphicParams, ColorDef, LinePixels, FillFlags, Gradient, RenderMaterial } from "@bentley/imodeljs-common";
  +import { GraphicParams, ColorDef, LinePixels, FillFlags, Gradient, RenderMaterial, TextureMapping } from "@bentley/imodeljs-common";
  import { compareNumbers, compareBooleans } from "@bentley/bentleyjs-core";
  export namespace DisplayParams {
  @@ -29,7 +29,10 @@ export class DisplayParams {
  public readonly type: DisplayParams.Type = DisplayParams.Type.Mesh;
  public readonly material?: RenderMaterial; // meshes only
  public readonly gradient?: Gradient.Symb;
  - // ###TODO: public textureMapping: TextureMapping; // only if m_material is null (e.g. gradients, glyph bitmaps) // TextureMapping doesn't exist yet!!!
  + // ###TODO
  + // textureMapping should be a getter that uses material's textureMapping if defined otherwise uses gradient to create textureMapping
  + // for now just filling in a default map
  + public readonly textureMapping: TextureMapping = new TextureMapping(); // only if m_material is null (e.g. gradients, glyph bitmaps)
  public readonly lineColor: ColorDef; // all types of geometry (edge color for meshes)
  public readonly fillColor: ColorDef; // meshes only
  public readonly width: number = 0; // linear and mesh (edges)
  