Saving state and getting the main window out of the way

Dear developer,

A while ago I made some changes to the source of QuickSynergy to make it not quit when I closed the window. I also made QuickSynergy save its running state when I quit the application, so that when I launch QuickSynergy again, it will start running if it was running when I quit it. It would do nothing when it was not running of course. And it also now remembers the last shown tab on quit. Can also come in quite handy.

Hope you like the commits!
Cheers.