Implement support for ranges in neighbourhood-definitions

Rather than specifying:
```
neighbourhood foobar {
(-2, 2), (-1, 1), (0, 2), (1, 2), (2, 2),
(-2, 1), (-1, 1), (0, 1), (1, 1), (2, 1),
(-2, 0), (-1, 0), (1, 0), (2, 0),
(-2,-1), (-1,-1), (0,-1), (1,-1), (2,-1),
(-2,-2), (-1,-2), (0,-2), (1,-2), (2,-2)
}
```
The following should be possible:
```
neighbourhood foobar {
(-2, 2) -> (2,-2)
}
```

The issue names neighbourhood-definitions but no files or tests. Start by locating the parser or entry point for neighbourhood definitions and compare how coordinate lists are handled. Confirm the intended expansion of the shown arrow form and add coverage demonstrating the equivalent coordinates; done when the range syntax is accepted.

Written by the indexing model from the issue text.