devel/eric: update to 21.7 release+

It fixes a few bugs and introduces these new features:

• Tasks
• made the task properties dialog adapt to the task kind
• added code to get typed manual tasks

• UML Diagrams
• extended the class items to show class attributes
• added code to load a saved UML diagram via the file browser or the project others browser
• improved the diagram layout of the Import Diagram and the Application Diagram
• added code to save and load diagrams as JSON files
• changed code to print diagrams