Model print and compare user customisable style (#5866)

* New feature: Model print and compare customisable style

* Layout cosmetics.

* File handling tweak
Message cosmetics

companion/src/comparedialog.ui

@@ -43,6 +43,9 @@
        <property name="text">
         <string>To compare models, drag and drop them anywhere in this window.</string>
        </property>
+       <property name="wordWrap">
+        <bool>true</bool>
+       </property>
       </widget>
      </item>
      <item>
@@ -65,6 +68,13 @@
        </property>
       </widget>
      </item>
+     <item>
+      <widget class="QPushButton" name="styleButton">
+       <property name="text">
+        <string>Style</string>
+       </property>
+      </widget>
+     </item>
      <item>
       <widget class="QPushButton" name="printButton">
        <property name="text">