trade: fix layout of packing list printout

There was an empty column right to quantity unit for all packing list
lines

bt5/erp5_trade/SkinTemplateItem/portal_skins/erp5_trade/PackingList_viewAsODT.xml

@@ -447,7 +447,7 @@ AAA=</string> </value>
               <text:p text:style-name=\'Item_20_Table_20_Title_20_Left\'><span tal:replace=\'orig_message\'/></text:p>\n
               <text:p text:style-name=\'Item_20_Table_20_Title_20_Left\' tal:condition=\'python:translated_message != orig_message\'><span tal:replace=\'translated_message\'/></text:p>\n
             </table:table-cell>\n
-            <table:table-cell table:style-name=\'Tableau1.A2\' office:value-type=\'string\' tal:define=\'orig_string string:Description; orig_message python:unicode(here.Base_translateString(orig_string, lang=default_language),"utf-8"); translated_message python:unicode(here.Base_translateString(orig_string),"utf-8")\'>\n
+            <table:table-cell table:number-columns-spanned="2" table:style-name=\'Tableau1.A2\' office:value-type=\'string\' tal:define=\'orig_string string:Description; orig_message python:unicode(here.Base_translateString(orig_string, lang=default_language),"utf-8"); translated_message python:unicode(here.Base_translateString(orig_string),"utf-8")\'>\n
               <text:p text:style-name=\'Item_20_Table_20_Title_20_Left\'><span tal:replace=\'orig_message\'/></text:p>\n
               <text:p text:style-name=\'Item_20_Table_20_Title_20_Left\' tal:condition=\'python:translated_message != orig_message\'><span tal:replace=\'translated_message\'/></text:p>\n
             </table:table-cell>\n
@@ -460,6 +460,7 @@ AAA=</string> </value>
               <text:p text:style-name=\'Item_20_Table_20_Title_20_Left\'><span tal:replace=\'orig_message\'/></text:p>\n
               <text:p text:style-name=\'Item_20_Table_20_Title_20_Left\' tal:condition=\'python:translated_message != orig_message\'><span tal:replace=\'translated_message\'/></text:p>\n
             </table:table-cell>\n
+            <table:covered-table-cell/>\n
           </table:table-row>\n
         </table:table-header-rows>\n
         <table:table-row table:style-name=\'Tableau1.3\' tal:repeat=\'line_dict python:data_dict["line_list"]\'>\n
@@ -479,7 +480,7 @@ AAA=</string> </value>
                       tal:content=\'python:line_dict["reference"]\'\n
                       tal:attributes=\'text:style-name style_name\'>ref</text:p>\n
             </table:table-cell>\n
-            <table:table-cell table:style-name=\'Tableau1.A3\' office:value-type=\'string\'>\n
+            <table:table-cell table:number-columns-spanned="2" table:style-name=\'Tableau1.A3\' office:value-type=\'string\'>\n
               <text:p text:style-name=\'Table_20_Contents\' tal:attributes="text:style-name left_style_name"><tal:block tal:repeat="line line_dict/description"><tal:block\n
                     tal:replace="line"/><text:line-break tal:condition="not:repeat/line/end"/></tal:block></text:p>\n
             </table:table-cell>\n
@@ -493,6 +494,7 @@ AAA=</string> </value>
                       tal:attributes=\'text:style-name style_name\'>qty_u</text:p>\n
             </table:table-cell>\n
           </tal:block>\n
+          <table:covered-table-cell/>\n
         </table:table-row>\n
         <table:table-row table:style-name=\'Tableau1.5\'>\n
           <table:table-cell table:style-name=\'Tableau1.A5\'\n