Add combo box for fast search engine switch

I wanted something like that long time ago and now i have time for that...
Well actually i need time to test that and i will be able to do that on weekends... i hope. Since i have no experience with QT i guess it maybe faulty... anyway once i will get how to build qB i will find out it :)
Who would thought that it is so difficult to build qB....

And i guess someone can even review me :)

P.s. reasoning behind it is that sometimes i really need to get search result from one specific engine... Instead of all enabled at once