Fix issue on note creation caused by commit bce7778

[jeanphilippegg]

I made this pull request to fix my mistake as reported in #357. Sorry about this!

I may add another commit soon. I feel like there is something awkward with the way we handle the title and the renaming convenience commands. For example, denote-rename-file-signature called on a file that is not yet a Denote file. This is a case I may not have considered in my refactoring.

Anyway, don't wait to merge this current pull request.

resolves #357

[jeanphilippegg]

Actually, never mind my previous comment. I checked out the code from a few weeks ago and tested denote-rename-{add/remove}-signature and they also duplicate the id if we cannot find a title. Same thing with denote-dired-rename-marked-files-with-keywords.

[protesilaos]

Merged, thank you!