Version 1.0.1 - Restore Alignment Plugin, Refactoring, and Fix Flatpak

Changes:

• Restore the alignment plugin
• Fix corruption of Namespace during undo
• Start the app as a Gtk.Application
• Combine the UIManager service into the ActionManager
• Fix Flatpak packages
• Refactor the UML module to make it more atomic

Version 1.0.0 - Python 3 and PyGObject

• Port to Python 3
• Port from GTK+ 2 and PyGTK to GTK+ 3 with PyGObject
• Drop use of etk.docking
• Overhaul the README
• Add contributing guide and code of conduct
• Adopt Black as code formatter
• Add CI/CD for Windows, macOS, Linux with Azure-Pipelines and ReadTheDocs

Port to Python3 and PyGObject

1.0.0rc1

Update version to 1.0.0rc1