Renamed directive to more general "presentation", updated internal API to match this change.
Handle case where page change event is received while file is still downloading.
Allow subscribers to control the presentation, too.
All participants should have the same permissions and be able to present/upload files.
Updated style of controls, show page number.
Added information about dropping a PDF to present it.
Handle conference cases where participants join/leave existing presentation.
Automatically scale presentation to visible area.