AVI export related changes
Fixed: AVI export prefers built in AVI viewer to shell one
Changed: AVI export shell viewer option is not available in exclusivity mode (since the shell associated application window will go background)
Fixed: Shell open for media files is not available in exclusivity mode
Changed: AVI export default changed to recompress due to continuing Morgan Multimedia codec MJPG troubles; recompression codec autodefaults to JPEG
Fixed: JPEG encoder and deceder DirectShow filters pass EndOfStream notifications downstream
Fixed: AVI viewer pauses playback once end of media file is reached