Merge pull request #5 from jonnius/master

German translation updated
Refresh changed from idle_add to timeout_add to prevent lags in some cases on some systems.
Added app icon click option to quit application.
Refresh: back to idle_add but keep timeout_add to prevent significant lags.
Updated README.md: dependencies to build under Fedora.
Merge branch 'master' of https://github.com/dbfin/gnome-shell-extension-yawl
Changed some default parameters.
Change option to show all non-minimized windows with single click so that it will show next window once focused.
Set preview clone's initial opacity to 0.
Delay showing window previews to prevent accidental showing.
Do not initiate window attention blinking for non-interesting windows.
Option to scroll over panel to change workspace moved to Add-ons, added Add-ons categories.
Added support for smooth mouse scroll.
Class Clicked: added option to disable single clicks.
Panel Apps: switch from internal scroll-event handler to class Clicked.
Prevent multiple scroll events coming at the same time.
Split some preference messages to "pick up" other translations.
Make scroll-to-search-windows feature optional.
Prevent thumbnail expansion if hovered after window was destroyed.
Allow 0 x and y when passed to YAWLPanel constructor.