that displays the url currently completed.
Also add an option to disable the "switch tab" offer.
If enabled the user can press "Shift" to load the url in the current tab instead of switching tab.
I tried to copy behaviour of firefox. I hope I did not miss a bit...
- fixed occasional flickering when typing in address bar
- support for opening completions with pressing Down key
- support for selecting completions with Tab key
closes#105