Update windows watcher to send a single rename event with both the old and new path

[iwubcode]

Here's the fix for #44 .

A general comment for you to consider in the future, could we avoid heap allocation by using an optional instead? This would also allow us to leverage the copy constructor here.

[e-dant]

could we avoid heap allocation by using an optional instead? This would also allow us to leverage the copy constructor here.

Something like that sounds nice. However, we can't avoid a heap allocation unless we make the event structure non-recursive. (Need some indirection in that case.)

It's recursive because:

Currently, the only possible associated event is a renamed-to event. In the future, we may store other kinds of associated events there. Ownership changes are a good candidate. This kind of structure allows more room for future changes if needed, although admittedly the intended use of associated events may be a bit less obvious to the user than I’d like.

It was meant to give us some room for future changes. There are no filesystem events that require more than a pair of events, so it might not be necessary at all.

We can probably just store a bare event lookalike with just the path/path-type/event-type/event-time in an optional or something similar.

[e-dant]

This can go out in a patch release soon.

Our Conan friends tend to be really on top of updates, so if that's something you use then this should be available there some time shortly after.