Lexical Table editor, move 'Merge or Delete ...' action buttons from Parameters zone to Main Action Toolbar

1. 'Merge or Delete columns' and 'Merge or Delete lines' buttons open dialogs that modify the content of the lexical table. Thus they are not just PARAMETERS, they are means to ACT on the table.
   -> To provide a direct access to their action, we can move the buttons at the top level toolbar, for example between the Property values menu and the Compute button.
2. 'Merge or Delete lines' action is much more often used than the 'Merge or Delete columns'. For an occidental UI that reads from left to right it is better if the more often action is access from the left -> Move the 'Merge or Delete lines' to the left (before) the 'Merge or Delete columns' button
3. 'Merge lines' action is much more often used than the 'Delete lines' action. For an occidental UI that reads from left to right it is better if the more often action is access from the left -> Move the 'Merge lines' button to the left (before) the 'Delete lines' button
4. 'Merge columns' action is more often used than the 'Delete columns' action. For an occidental UI that reads from left to right it is better if the more often action is access from the left -> Move the 'Merge columns' button to the left (before) the 'Delete columns' button