Move undo/redo from context menu to toolbar.

And reorder buttons in toolbar.

Signed-off-by: Vivek Rai <vivekraiiitkgp@gmail.com>
Move toolbar out of edit track.

And prettify track labels with chevron.

Signed-off-by: Anurag Priyam <anurag08priyam@gmail.com>
Signed-off-by: Vivek Rai <vivekraiiitkgp@gmail.com>