In addition to security rights (was already implemented), now follow
`create="0"` / `edit="0"` / `delete="0"` attributes one can set onto the
`timeline` tag, same as in other Odoo views.
When an item label does not fit in its date-range box, overflow
according to
https://visjs.github.io/vis-timeline/examples/timeline/items/rangeOverflowItem.html
Previous CSS code was already trying to do that, but was selecting
`.vis-item.vis-item-content` instead of `.vis-item .vis-item-content`.
Displaying overflow text brings up layout issues solved by removing the
forced-100% width instruction.
This change also adds highlight when hovering a box, which is useful on
text that has overflown (as it has no borders).
Houzéfa Abbasbhay
CarlosRoca13
tarteo