Add example model: Screwdirver

Backpacker example got removed.

resources.qrc

@@ -8,13 +8,13 @@
         <file>resources/tree-vline.png</file>
         <file>resources/material-demo-model.ds3</file>
         <file>resources/model-addax.ds3</file>
-        <file>resources/model-backpacker.ds3</file>
         <file>resources/model-bicycle.ds3</file>
         <file>resources/model-dog.ds3</file>
         <file>resources/model-cat.ds3</file>
         <file>resources/model-giraffe.ds3</file>
         <file>resources/model-meerkat.ds3</file>
         <file>resources/model-mosquito.ds3</file>
+        <file>resources/model-screwdriver.ds3</file>
         <file>resources/model-seagull.ds3</file>
         <file>resources/model-procedural-tree.ds3</file>
         <file>resources/triangle.png</file>

src/documentwindow.cpp

@@ -560,13 +560,13 @@ DocumentWindow::DocumentWindow() :
     m_openExampleMenu = new QMenu(tr("Open Example"));
     std::vector<QString> exampleModels = {
         "Addax",
-        "Backpacker",
         "Bicycle",
         "Cat",
         "Dog",
         "Giraffe",
         "Meerkat",
         "Mosquito",
+        "Screwdriver",
         "Seagull",
         "Procedural Tree"
     };