Scene deleting

[Dgzt]

Added submenus to scene menu.

• Open - Opens the selected scene
• Delete - Deletes the scene

The Delete button is disabled on the current selected scene:

After clicked to the Delete button then the application shows a confirmation modal:

[Dgzt]

I will add Rename button between Open and Delete in the next merge request.

[JamesTKhan]

This looks good, and very useful feature.