Alpha8 AppImage

[Jean-Baptiste Mardelle]

Hi all,

Following latest version and feedback, I just uploaded the latest AppImage 
that should fix following issues:

* Fix crash on composition selection
* Implement composition grouping
* Fix random clip move on group move
* Fix clip move canceled if dragging over a clip in another track
* Fix timeline cursor showing in the track headers zone
* Reimplement project duration
* Fix group cut
* Implement composition copy / paste
* Fix missing scrollbars in timeline

The updated version can be 

https://files.kde.org/kdenlive/unstable/kdenlive-18.04-alpha8.AppImage.mirrorlist

Thanks to all those who provided feedback

Regards
Jean-Baptiste