Collection that matches the scheduled clips in melted

Signed-off-by: Tomas Neme <lacrymology@gmail.com>
fix prototype calls

Signed-off-by: Tomas Neme <lacrymology@gmail.com>
keep a MeltedCollection around

Signed-off-by: Tomas Neme <lacrymology@gmail.com>
flatten the collection of collections into an array of Medias

Signed-off-by: Tomas Neme <lacrymology@gmail.com>