Picture source now supports 'media' attribute.
Also fixed keying mistakes brought by previous commits adding picture support: keyed picture to get transitions right, altered source keying to contain both imgIndex and sourceIndex to avoid key duplicates.
Picture source now supports 'media' attribute. Also fixed keying mistakes brought by previous commits adding picture support: keyed picture to get transitions right, altered source keying to contain both imgIndex and sourceIndex to avoid key duplicates.