Re-enable script

* Fix wrongly checking for empty array.
Pass arguments when launching alternate editor
Improve detection of cron script
Don't perform any synchronisation
Add new features

* Improve output of messages.

* Move backup into own directory. Directory has the form `mmyy'.

* Discard backups whose contents have not changed from the last one.

* Only keep the most recent backups.
Remove MD5 comparison to previous last backup

Doesn't work. MD5 hash differs even when contents are the same because the
backup file names are different.