erp5_safeimage: Move Mixin definitions to PortalTypeTypeMixin

       Use the proper way to include Mixin into a portal type

bt5/erp5_safeimage/PortalTypeTemplateItem/portal_types/Image%20Tile%20Transformed.xml

@@ -50,14 +50,6 @@
               <tuple/>
             </value>
         </item>
-        <item>
-            <key> <string>type_mixin</string> </key>
-            <value>
-              <tuple>
-                <string>BaseExtensibleTraversableMixin</string>
-              </tuple>
-            </value>
-        </item>
       </dictionary>
     </pickle>
   </record>

bt5/erp5_safeimage/PortalTypeTypeMixinTemplateItem/type_mixin.xml

+<type_mixin>
+ <portal_type id="Image Tile">
+  <item>BaseExtensibleTraversableMixin</item>
+ </portal_type>
+ <portal_type id="Image Tile Transformed">
+  <item>BaseExtensibleTraversableMixin</item>
+ </portal_type>
+</type_mixin>
\ No newline at end of file

bt5/erp5_safeimage/bt/template_portal_type_type_mixin_list

+Image Tile Transformed | BaseExtensibleTraversableMixin
+Image Tile | BaseExtensibleTraversableMixin
\ No newline at end of file