Remove string attribute from views

issue2350

view/package_form.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. -->
-<form string="Package">
+<form>
     <label name="type"/>
     <field name="type" widget="selection"/>
     <label name="code"/>

view/package_list.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 string="Packages">
+<tree>
     <field name="rec_name"/>
     <field name="shipment"/>
     <field name="type"/>

view/package_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 string="Packages">
+<tree>
     <field name="rec_name"/>
     <field name="type"/>
     <field name="shipment"/>

view/package_type_form.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. -->
-<form string="Package Type">
+<form>
     <label name="name"/>
     <field name="name"/>
     <notebook colspan="4">

view/package_type_list.xml

@@ -1,6 +1,6 @@
 <?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 string="Package Types">
+<tree>
     <field name="name"/>
 </tree>