I implemented a defir and Emmy based plug-in, and an intrusion - intensive mount thread async. Can you merge it into the main branch

[aadog]

• [ ] GopherLua is a Lua5.1 implementation. You should be familiar with Lua programming language. Have you read Lua 5.1 reference manual carefully?
• [ ] GopherLua is a Lua5.1 implementation. In Lua, to keep it simple, it is more important to remove functionalities rather than to add functionalities unlike other languages . If you are going to introduce some new cool functionalities into the GopherLua code base and the functionalities can be implemented by existing APIs, It should be implemented as a library.

Please answer the following before submitting your issue:

1. What version of GopherLua are you using? :
2. What version of Go are you using? :
3. What operating system and processor architecture are you using? :
4. What did you do? :
5. What did you expect to see? :
6. What did you see instead? :

defer example:

defer defer print("aaa") end print("aaa1") end

output: aaa1 bbb

async example:

Each Lua thread mounts a go thread to perform background tasks, such as time. Sleep, which is implemented by hook