[TW-82] Cross referencing task IDs

_John Florian on 2009-12-21T14:47:21Z says:_

It would be useful if it were possible to do something like:

```
$ task add Put out house fire.
Created task 42
$ task add Fix fire hydrant.
Created task 43
$ task annotate 42 See also #43.
Annotated 42 with 'See also #43.'
$ task annotate 43 See also #42.
Annotated 43 with 'See also #42.'
```

The example is kind of lame because it suggests a dependency, but that's not really the intent. Obviously this can be done now, but if the IDs shift, the annotations will become incorrect. The gist of the feature would be that these somehow get adjusted behind the scenes. Present workarounds might involve a project or tags, but I can see cases where the projects are distinct. I suppose the annotation could suggest something like 'See tag foo'.

No pressing need now, just thought the idea warranted recording for future consideration.