calendar.view.week.Component: drag:end animations

this feel a bit inconsistent: we get resize and drag animations when moving inside the same column, except when dragging an event before another one (in which case a store.sort() happens and the event dom nodes get switched).

we also do not get animations in case we drag an event into a different column.

to resolve this, we need a custom animation: get the DOMRects of the old event and of the last proxy el position. Create an absolute positioned clone of the event at the old position, move it to the new spot via CSS transitions (left, top, height), then move the real event node instantly.

the drag:end animation should be optional (vm config to disable it).