This way we can improve the heuristic used for mapping notes to
timeline events, by taking the row into account. Also, by marking
notes as loaded when loading them we avoid accidentally dropping
them by restricting to ranges.

Change-Id: I031389880571805788c910728ee89333a5cd4727
Task-number: QTCREATORBUG-16542
Reviewed-by: Joerg Bornemann <joerg.bornemann@qt.io>