Display legal notice on screen center

Changelog

@@ -5,6 +5,7 @@
    - BUGFIX: Avoid main window flashing on startup (closes #703984)
    - BUGFIX: Improved hostname resolution code
    - BUGFIX: Dropped dependency on libboost-thread
+   - BUGFIX: Display legal notice on screen center
    - I18N: More dialog buttons are now translated (by Vladimir Golovnev)
    - I18N: Fix translation of size units (by Vladimir Golovnev)
 

src/main.cpp

@@ -106,6 +106,8 @@ public:
     msgBox.setWindowTitle(tr("Legal notice"));
     msgBox.addButton(tr("Cancel"), QMessageBox::RejectRole);
     QAbstractButton *agree_button = msgBox.addButton(tr("I Agree"), QMessageBox::AcceptRole);
+    msgBox.show(); // Need to be shown or to moveToCenter does not work
+    msgBox.move(misc::screenCenter(&msgBox));
     msgBox.exec();
     if(msgBox.clickedButton() == agree_button) {
       // Save the answer