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如果Polyline不为简单的几何图形，则求出其自相交的点。如果FromPoint和ToPoint重合也一并返回。
实现逻辑：
一、创建IMulitPoint pTargetPoint
二、判断Polyline是否首尾相接，如果首尾相接，将点加入到pTargetPoint;
三、判断Polyline是否为简单的几何图形，如果不是则进行以下步骤：
1）得出Polyline中所有Path的起点和终点，List
2）将Polyline简单化，得出所有Path在LstOrigin中找不到的起点和终点，添加到pTargetPoint中
第三步的代码：
private IMultipoint getInersectPoint(IPolyline pPolyline)
{
IGeometryCollection pGeoColl = pPolyline as IGeometryCollection;
List lstPoint = new List();
for (int i = 0; i < pGeoColl.GeometryCount; i++)
{
IPath pPath = pGeoColl.get_Geometry(i) as IPath;
IPoint pTemp = lstPoint.Find(p => (p.X == pPath.FromPoint.X && p.Y == pPath.FromPoint.Y));
if (pTemp == null) lstPoint.Add(pPath.FromPoint);
pTemp = lstPoint.Find(p => (p.X == pPath.ToPoint.X && p.Y == pPath.ToPoint.Y));
if (pTemp == null) lstPoint.Add(pPath.ToPoint);
}
ITopologicalOperator2 ptopo = pPolyline as ITopologicalOperator2;
ptopo.IsKnownSimple_2 = false;
ptopo.Simplify();
IMultipoint pMultipoint = new MultipointClass();
IPointCollection pPointColl = pMultipoint as IPointCollection;
for (int i = 0; i < pGeoColl.GeometryCount; i++)
{
IPath pPath = pGeoColl.get_Geometry(i) as IPath;
IPoint pTemp = lstPoint.Find(p => (p.X == pPath.FromPoint.X && p.Y == pPath.FromPoint.Y));
if (pTemp == null) pPointColl.AddPoint(pPath.FromPoint);
pTemp = lstPoint.Find(p => (p.X == pPath.ToPoint.X && p.Y == pPath.ToPoint.Y));
if (pTemp == null) pPointColl.AddPoint(pPath.ToPoint);
}
return pMultipoint;
}
