Cleanup & refactor timeline code, switch to Qml.
After the January 2017 developer meeting: https://notes.kde.org/p/kdenlivedevel01 we took the following decisions:
- We start a new timeline from scratch
- Alcinos starts writing headers, so we try to start from a good design. We can then start implementing the functions
- JB takes a look at Qml to replace QGraphicsView, we should have a clear separation between functional code and display code
- We avoid duplicating operations like in the current code where we have to perform everything twice (on MLT and on the QGraphicsView)
- Once we get a first working draft, we organize a brainstorming to rethink the timeline display and user interaction
Discussions and sub-tasks should be centralized here