Proposal: Additional Diagram Controller "Karel the Robot"

[codemanyak]

Having layed the foundations with issues #443 and #910, we might add a new DiagramController next to Turtleizer, which makes the classic setting "Karel the Robot" by Richard E. Pattis available within Structorizer, particularly for learning and teaching purposes. There are of course plenty of implementations and adaptations around (e.g. https://sourceforge.net/projects/keditor/, https://github.com/fredoverflow/karel, https://sourceforge.net/projects/karel-3d-webgl/, https://sourceforge.net/projects/karelwin/, https://karel.csbridge.org, etc.) but this is also sort of evidence that the the concept is still valuable. A first version would just provide a window with the sizeable flat street / avenue grid and rulers, where walls, the robot icon(s), and "beepers" may be placed both via the GUI or with API procedures. And there would be the usual procedures and functions in the Diagram Controller API then. The "situation", i.e. the size of the "city" and the initial placement of walls, beepers, and robot(s) shall be saveable to and loadable from respective files (e.g. in XML or CSV format). So it would be a very organic combination between the provided instruction primitives and the diagram-based control structures. Of course, the user might also employ all built-in operators, functions, and procedures, but they are of limited help for the solution of the typical Karel world tasks. So the concept is hardly spoiled. Later on, some extensions might be possible.