Overview as timeline/Gantt view

For planning and overview purposes, we need a view similar to the calendar view, however on a timeline/Gantt schedule > dates horizontal, campaigns and content items vertical.

It should be possible to adjust what kind of time unit we would want to see (months or weeks, depending on what kind of planning we would like to do).

It would be even better if there could be some kind of hierarchy, so that one could view campaigns for the whole year e.g. and then expand and see what kind of items are included in the campaign.