Finishing EBUCore viewer/editor

- Several changes in the metadataWindow source to avoid crashes when
files aren not readables or not compatibles with the ebucore data model.
- Several informations about the ebucore file are displayed in the right
side of viewer.
- Left side of the viewer is hided when no ebucore file is detected.
- Refresh dynamicly the both side of the viewer.
- Detect file size
- Minimalistic ebucore skeleton generation