Rename TooltipHelper to DefaultTooltipHelper so that the name can be used for the interface.
Create a `br.presenter.tooltip-helper` alias that by default points to br/presenter/control/tooltip/DefaultTooltipHelper

Users can provide a different implementation of the helper by overriding the alias.
Merge pull request #1052 from janhancic/feature/allow-tooltiphelper-override

Feature allow tooltip helper override