Codemap

Works done

- context menu for change the ratio of code map
- turned off or modified event handlers
- adding/removing/reordering blocks in the '.script_workspace' simulated in code_map

Works left

- [ ] add function to recursively add blocks that are loaded from example or etc (take care of genuine spec such as 'count')
- [ ] add click event handler to code map (there is a scale issue)
- [ ] draw a rectangle for the view port of '.scripts_workspace' (there is a scale issue)