PowerShell Script to get all SharePoint Workflows in Farm

The following PowerShell scripts enumerate all SharePoint 2010 and 2013 Workflows in your environment.

SharePoint 2010 Workflows

Thanks to Nico Martens for sharing the PowerShell script Get all workflows in all sites and lists
However, this script does not enumerate SharePoint 2013 Workflows, only 2010 Workflows.

SharePoint 2013 Workflows

The following script example enumerates all SharePoint 2013 Workflows for your farm.
As a special feature, the script will highlight all Workflows that have been modified during the last 7 days.