Do not allow changing the section of accounting line

By changing the section one can enter accounting transaction lines on a
different section bypassing the security because usually only the section at
the transaction level is taken into account for roles assignements.

bt5/erp5_accounting/SkinTemplateItem/portal_skins/erp5_accounting/AccountingTransactionLine_view/my_source_section_title.xml

@@ -10,6 +10,7 @@
             <key> <string>delegated_list</string> </key>
             <value>
               <list>
+                <string>editable</string>
                 <string>title</string>
               </list>
             </value>
@@ -71,6 +72,10 @@
             <key> <string>values</string> </key>
             <value>
               <dictionary>
+                <item>
+                    <key> <string>editable</string> </key>
+                    <value> <int>0</int> </value>
+                </item>
                 <item>
                     <key> <string>field_id</string> </key>
                     <value> <string>my_source_section_title</string> </value>

bt5/erp5_accounting/SkinTemplateItem/portal_skins/erp5_accounting/AccountingTransactionLine_viewDestination/my_destination_section_title.xml

@@ -10,6 +10,7 @@
             <key> <string>delegated_list</string> </key>
             <value>
               <list>
+                <string>editable</string>
                 <string>title</string>
               </list>
             </value>
@@ -71,6 +72,10 @@
             <key> <string>values</string> </key>
             <value>
               <dictionary>
+                <item>
+                    <key> <string>editable</string> </key>
+                    <value> <int>0</int> </value>
+                </item>
                 <item>
                     <key> <string>field_id</string> </key>
                     <value> <string>my_destination_section_title</string> </value>

bt5/erp5_accounting/bt/revision

-1530
\ No newline at end of file
+1531
\ No newline at end of file