Feature Request: Improved support for missing nodes

[parisba]

Feature Request: Improved support for missing nodes

The following behaviour would be ideal:

• when writing a jump to a node that doesn't exist, it should offer to create a stub for that node for you in the current file (or any file of their choice, if that's possible)
• when creating a node that's not jumped to by any jumps, a warning should be issued
• an error should be generated if a <<jump>> to a node that doesn't exist is present