Redesigned annotation bubble

The annotation bubble has a new layout: a smaller avatar, the author and the date on the same line, and an "x" button to close it.

Annotations stored as comments now show the same "Reply", "Share", "Edit" and "Delete" buttons as the Comments tab, plus a "View thread" button showing the number of replies when there are some. "Share" opens a dialog with the permalink of the annotation, and that dialog now has a button to copy the link to the clipboard. See the Annotation Application for how to view, edit and delete annotations.