qvm-template: Disable multi-selection for simplicity.

ui/qvmtemplate.ui

@@ -31,7 +31,7 @@
        <set>QAbstractItemView::AllEditTriggers</set>
       </property>
       <property name="selectionMode">
-       <enum>QAbstractItemView::MultiSelection</enum>
+       <enum>QAbstractItemView::SingleSelection</enum>
       </property>
       <property name="itemsExpandable">
        <bool>false</bool>