When adding a previously-deleted file, emit 'add', not 'change'

[erezarnon]

Turns out #379 is an issue for files as well as directories, but manifests differently.

[erezarnon]

I've fixed the issue on linux. My test fails on osx, but I can't fix it because I don't have a mac. First version of this pull request was with commit erezarnon@db6f928, which failed even more osx tests than the current commit. I hoped maybe the issue didn't exist on osx, so tried to fix with c5a3c2e by checking for !this.options.useFsEvents. But now the issue still exists on osx.

[es128]

This scenario (almost) is already tested. https://github.com/paulmillr/chokidar/blob/master/test.js#L352

If a file is unlinked and re-added in quick succession, it is represented as a change event deliberately by default (with atomic: true).

So perhaps basing the change on if (!this.options.atomic) would be the appropriate approach.

[erezarnon]

The mapping of add->change still works. If we base it on this.options.atomic, the bug will exist when there's a delay between unlink and add. Also, I think Chokidar should understand internally that the event is file creation, even if it will map the event before emitting it.

Either way, this would still fail the test cases, right?

[es128]

Ok, right. I'll need to investigate the Mac situation.

[es128]

Thanks! Landed as 5a6315f