Add a command line script to manage backups

[RKrahl]

Add another command line script to manage backups. It should be designed to be called regularly as a background job, (e.g. from cron or a systemd timer).

Features:

• It must at least support creation of backups.

• Read configuration from a file. On creation of an archive the following options should be set from the configuration file:

  • directories that should be archived,
  • exclude patterns,
  • directory to store the archive,
  • a template for the archive file name,
  • tags to be added to the archive,
  • directory to look for previous backups when creating incremental backups.

• Support creation of incremental backups. This may be controlled by a command line flag.