Review editable attribute

Use top for main tree and bottom when inside a field.

issue8430
review255581002

view/line_tree.xml

@@ -1,7 +1,7 @@
 <?xml version="1.0"?>
 <!-- This file is part of Tryton.  The COPYRIGHT file at the top level of
 this repository contains the full copyright notices and license terms. -->
-<tree editable="bottom">
+<tree editable="top">
     <field name="company"/>
     <field name="employee"/>
     <field name="date"/>