Add option to create automated custom tasks/items

[andergmartins]

We could add an option to specify if the custom item should be manually or automatically checked. If manually checked, it is based on what we have right now. If automatically checked, it should display a code box where the user can type a custom JS code for manipulating the task/item in the checklist.

The option for creating a custom JS code should give clear instructions on how to proceed. Ask for specific functions and display a simple but clear help text.

Probably a pro feature due the required effort.