Media control improved.
Code was cleaned.

Fixed SANKORE-902 - undo and redo works fine for deleted Media Items.

toolBar size depends on zoom.
audio items has title and borders.

Audio items cannot be resized in vertical dimension because there are no useful content.

Audio and Video items has minimal dimensions.

- locked items is not editable now.
- toolbar for text item hides when item is locked

Fixed behavior of toolbar:
toolbar of media items hides after 5s of idle.