add cookie功能

Signed-off-by: youzipi <blake_12@qq.com>
fix 用cookie加载节点时数据库报错：Operation not allowed after ResultSet closed
ps：我好像遇到并发的问题了
前n次加载完成时，展开cookie中的节点。

Signed-off-by: youzipi <blake_12@qq.com>
Merge branch 'master' of github.com:youzipi/KnowledgeTree
Signed-off-by: youzipi <blake_12@qq.com>