Fix tabbar popups on wrong monitor

* Fixes #45
* Widget position should be checked against screen.bottomRight,
  rather than screen.height and screen.width
Add ctrl/shift key modifiers for link click

* ctrl+click = open in new background tab
* shift+click = open in new tab
Merge pull request #47 from cgschwarz/ticket45_multimon

Fix tabbar popups on wrong monitor
Merge pull request #48 from cgschwarz/shiftclick_newtab

Add ctrl/shift key modifiers for link click
Minor consistency fixes
Add draft of proxy configuration UI
Rename section
Update items if data becomes available
Update also in case of model reset