MainWindow moved into a ui file

I am not fun of ui files. they mostly confuses me when I am developing. but I decided that the main window should be in a ui(user interface) file. at the end qtv4lcapture uses QT and that is a good way to organize things around. and added dependincies and building nodes to http://qtv4lcapture.sourceforge.net/.

I dont know much about how to write configure and autotools. if you know how to do it feel free to send me some configure.am or makefile.am. I am c++ developer ;)