title: How can i make a QList<QVector3D> unique
body: <p>I have a <code>QList</code> consist of <code>QVector3D</code>. A <code>QVector3D</code> represents a vertex or a point. This List holds also all vertices of a <code>STL-File</code>. The problem is that a vertex exist multiple times in the list. In need a list of the unique vertices of a STL-File. How can i implement it with <code>Qt 5.0.2</code>?</p>