Back up before destructive actions

[rivaldi8]

Steps to reproduce the behaviour

1. Do any destructive action, like deleting a transaction.

Expected behaviour

A backup has been done before the operation so the user is able to restore the data in case the action has been done by mistake.

Actual behaviour

The data can't be restored unless there was some backup with the previous state.

[rivaldi8]

Fixed in develop.

I've dealt with all delete-related actions I've found, but still might've missed some.