Notepad++ style unsaved document autosave and restore

[ThinkAndWander]

This feature request entails the following behaviors:

1. Periodically, auto-save unsaved documents to a temp directory
2. Auto-save unsaved documents when the app would normally close, such that it closes without needing to ask the user to save
3. Restore all opened documents, temp or otherwise, on reopening the application

This is based on how the popular software Notepad++ works on Windows.
It is a very effective pattern that surprisingly doesn't exist yet for xed despite its semi-advanced capabilities.

Similar issues:
#428, #607 (scoped to only disaster recovery)

Issue #226 is about restoring the session on app start, not explicitly for unsaved documents. It mentions a plugin everyone is praising that might be doing that as well.

It's also an issue from eight years ago, and Linux Mint is attracting some of the crowd from Windows, most who are not as technical. So they'll find it unhelpful when eventually they lose data by needing to close things, or forgetting how important something is when they go to close it, because they're unaware that xed has a plugin system or unaware of its plugins. It's a very core feature, I think, better fitting to be part of the app than outside it.

I am an outsider spurred by wanting something. For those who do work on xed, what do you think?