Resolve "“Add from Publication” modal on dance list editing page doesn't work."

This MR introduces the following changes:

• “Tom Select” autocomplete widgets are properly initialised on dynamically-loaded modals.
• The extra-info line in the autocompletion popup is set to something meaningful (the publisher in case of “Add from Publication …”, the list owner in case of “Add from Other List …”).
• Autocompletion proposals for “Add from Other List …” not only include the current user's own lists but also group-owned lists that are accessible to them.
• SSE reread notifications are sent correctly.

Closes #45 (closed).