arcigs engine在复制图层要素时发生错误：几何不能具有Z值

解决方法如下：

var featureRow = sourceFeatureClass.CreateFeature();
IGeometry pGeom = pFeature.Shape;
IZAware pZaware = pGeom as IZAware;
pZaware.DropZs();
pZaware.ZAware = false;
featureRow.Shape = pGeom;