add textured terrain entity example to Ground Clamping Sandcastle
add textured terrain entity example to Ground Clamping Sandcastle

oterral/cesium,AnalyticalGraphicsInc/cesium,CesiumGS/cesium,YonatanKra/cesium,josh-bernstein/cesium,geoscan/cesium,CesiumGS/cesium,YonatanKra/cesium,soceur/cesium,progsung/cesium,oterral/cesium,hodbauer/cesium,kaktus40/cesium,kaktus40/cesium,CesiumGS/cesium,AnalyticalGraphicsInc/cesium,jasonbeverage/cesium,likangning93/cesium,soceur/cesium,likangning93/cesium,likangning93/cesium,progsung/cesium,YonatanKra/cesium,CesiumGS/cesium,likangning93/cesium,YonatanKra/cesium,jasonbeverage/cesium,hodbauer/cesium,soceur/cesium,hodbauer/cesium,geoscan/cesium,josh-bernstein/cesium,oterral/cesium,CesiumGS/cesium,likangning93/cesium