-Extent ItemTable with delete and clear

Signed-off-by: Yang Xiong <yang.xiong@truepartner.cn>
update position with trade

Signed-off-by: Yang Xiong <yang.xiong@truepartner.cn>
del position when it come 0
完成仓位更新

Signed-off-by: Yang Xiong <yang.xiong@truepartner.cn>