Enhance command loop with option if file is deleted.

[sallner]

Connected with #184 and #224 we can now have a situation, where an unintentional deletion of a secrets file might occur:

1. A user creates a secrets file with members and configuration and saves it
2. This change is not checked in to a VCS
3. The user edits the file again an accidentally deletes the members section
4. The following interaction should have an four options: 4.1. edit -- opens editor with current data again 4.2. encrypt -- tries to encrypt current data again 4.3. quit -- quits and loses your changes (This should restore the status form step 2.) 4.4. delete -- deletes the secrets file (This should close the file and unlink it. The current behaviour of 4.3|quit)

[icemac]

This requires a too big change, I am not able to solve this issue now. I think the 2.3 release should not depend on it.