title: qmake: compile single cpp file into an executable
body: <p>I got a project in QT and I'd like to use qmake for compiling one additional cpp file that (into standalone executable) is not connected in any way to my application or even QT (it's very simple plain C++ program). Is there any way to do this without rebulding whole project structure? Do I need separate <code>.pro</code> file for every executable or is there any other way for simple compiling just one, plain C++ file?</p>