Allow content to oversize trigger width

[untemps]

The width of the tooltip can't exceed the size of the target so far. So the content has to adapt consequently. It would be nice to allow the width of the tooltip to be greater than the target one. We should keep a max width as it does not make sense for the content of a tooltip to exceed a certain size. Though, it might be useful to add a prop to manage this behaviour, like width: ['auto'|size]