Bring consistency between line and bubble options

[benmccann]

Bubble options are not prefixed with "point", but line options are. E.g. line controller has pointBorderColor, pointRadius, etc... For the bubble controller, we have borderColor, radius, ...

In 3.0, we should scope those options: dataset.point.radius, dataset.point.rotation or dataset.elements.point.radius ...

[etimberg]

This is out of v3 and we aren't going to change this now.