More enhancement to plugin system

The current plugin system is really good. However, I think that it would be better if we can extend it to require each plugin to define:

1.beforeActivationAction(): do something before activate a plugin, such as altering a table, copying or moving some files…
2.afterDeactivationAction(): return the original status of the system.

Do you think that would be neccessary?

Regards,

Dinh