* 347: Add hooks that run for the "extract" action: "before_extract" and "after_extract".
* 350: Fix traceback when a configuration directory is non-readable due to directory permissions.
* Add documentation navigation links on left side of all documentation pages.
* Clarify documentation on configuration overrides, specifically the portion about list syntax:
http://torsion.org/borgmatic/docs/how-to/make-per-application-backups/#configuration-overrides
* Clarify documentation overview of monitoring options:
http://torsion.org/borgmatic/docs/how-to/monitor-your-backups/