title: Qt, qt core inclusion necessary?
body: <p>I am getting confused about <strong>qmake</strong>. I read that i can include Qt special configuration to the <code>.pro</code> file like: <code>qt += core</code> I can also include <code>#include &lt;QtCore&gt;</code> in my project file. </p>
  
  <p>Is it necessary to make both includes, and why i even need to add the core to the <strong>.pro file</strong> if can include it in my project file!? </p>