Added bitmap-sdf library
Added bitmap-sdf library

CesiumGS/cesium,jasonbeverage/cesium,AnalyticalGraphicsInc/cesium,YonatanKra/cesium,likangning93/cesium,CesiumGS/cesium,likangning93/cesium,likangning93/cesium,CesiumGS/cesium,CesiumGS/cesium,progsung/cesium,YonatanKra/cesium,progsung/cesium,AnalyticalGraphicsInc/cesium,likangning93/cesium,YonatanKra/cesium,YonatanKra/cesium,jasonbeverage/cesium,CesiumGS/cesium,likangning93/cesium