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* Re-adding the ability to specify credential profile in the environment config.
* Adding init project command to help initialize a new Sceptre project.
* Adding init env command to help initialize a new Environment config.
* Adding diff command to display differences between the local and deployed stack template.
* Fixed error message displayed for empty environments.
* Adding ``environment_config`` to config template rendering.
* Adding ``on_failure`` parameter to stack config.
* Adding automatic renewal of expired credentials when assuming IAM Roles.
* Deprecating use of ``bash`` hook in favour of ``cmd`` hook.
* Deprecating use of ``asg_scheduled_actions`` hook in favour of ``asg_scaling_processes`` hook.
* Adding status colouring for output of describe-env command.
* Fix spelling mistakes in documentation.