Scaladoc display on completion & showToolTip

integrated with completion and 'Show tooltip'/F2 (which is not exactly hovers)
pinging @sschaef  because he should see the ugly handover from `getHoverInfo2` to `getHoverInfo`
<< I'm open for ideas on how to improve it which do not imply rewriting the `HtmlProducer` in `Scaladoc`
Yes, after tighter integration with the HtmlHover, it probably should (the reason it doesn't as it stands is because `HtmlHover` doesn't see the output of `gethoverInfo2`, and by extension, anything coming from a `HtmlProducer` — `HtmlProducer` works on its own`).