* add start_epg_group, stop_epg_group * fix imports * add graphics_on, graphics_off * add skip_items * add skip_to_item * add watermark_on, watermark_off
* add show content * add multi collection content * add smart collection content * add playlist content * fix infinite loop * add marathon content
* start to add content to scheduling engine * add first content instruction * add search content * allow scripted schedule creation * don't use scheduling engine in sequential playout builder, yet