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`
Also, the creation of HTML is not correct. `htmlContents` needs to be called inside of `HtmlHover.createHtmlOutput`.