add method RemoveChannelName in line

line.go

@@ -68,6 +68,13 @@ func (c *Line) SetChannel(name string) {
 	}
 }
 
+// 删除频道名，用于退出登录等操作
+func (c *Line) RemoveChannelName() {
+	if inx := strings.Index(c.channel, "@"); inx >= 0 {
+		c.channel = c.channel[inx+1:]
+	}
+}
+
 // 获取远程的地址
 func (c *Line) RemoteAddr() net.Addr {
 	if c.state == Connected {