Version 5.6

2018-08-06: v5.6

This release fixes several issues that was reported during the last
year. It also adds some new features:

  * Show timestamp in ISO format.
  * Add documentation about installation from distribution packages.
  * Replace call to ifconfig with ip.
  * Add last run timestamp to title on GD::Graph images.
  * Add "Section: admin" to debian control file.

Here are the full list of changes:

  - Fix typo in plugin sample.
  - Add documentation about installation from distribution packages.
  - Mark sysusagegraph using GD and GD::Graph as deprecated, it will
    be removed in next makor release.
  - Update year in copyright
  - Fix errors in handling dirty and blocked reports. Thanks to
    Barry Kwok for the report.
  - Replace call to ifconfig by ip when ifconfig is not a available,
    ifconfig has been removed in recent distributions like CentOs 7.
  - Show timestamp in ISO format. Thanks to Claus Regelmann for the
    feature request.
  - Add last run timestamp to title on GD::Graph images. Thanks to
    Claus Regelmann for the feature request.
  - Fix unwanted replacement of version number.
  - Add "Section: admin" to debian control file. Thanks to Matt
    Lewandowsky for the report.