delivery_usability: Move code from stock_packaging_usability_pp to delivery_usability

I don't use stock_packaging_usability_pp from OCA/stock-logistics-tracking because the feature is native since v11 (I didn't figure it out when I ported stock_packaging_usability_ul from v10 to v14 under the new name stock_packaging_usability_ul
I also improved the code to clean it up and use the native field for measured weight

delivery_usability/models/product_packaging.py

@@ -0,0 +1,31 @@
+# Copyright 2018-2021 Akretion (http://www.akretion.com)
+# @author Alexis de Lattre <alexis.delattre@akretion.com>
+# License AGPL-3.0 or later (http://www.gnu.org/licenses/agpl).
+
+from odoo import fields, models
+
+
+class ProductPackaging(models.Model):
+    _inherit = 'product.packaging'
+
+    # product.packaging is defined in the 'product' module and enhanced in the 'delivery' module
+    # I used to make the improvements on the datamodel of product.packaging in the OCA module
+    # 'stock_packaging_usability_pp' from OCA/stock-logistics-tracking,
+    # but I eventually figured out that the feature provided by 'stock_packaging_usability_pp'
+    # was native in the 'delivery' module via the wizard choose.delivery.package.
+    # So I stopped using 'stock_packaging_usability_pp' and I moved the datamodel changes
+    # here in the module 'delivery_usability'
+    name = fields.Char(translate=True)
+    weight = fields.Float(digits="Stock Weight", string="Empty Package Weight")
+    active = fields.Boolean(default=True)
+    # packaging_type is important, in particular for pallets for which
+    # we need a special implementation to enter the height
+    packaging_type = fields.Selection(
+        [
+            ("unit", "Unit"),
+            ("pack", "Pack"),
+            ("box", "Box"),
+            ("pallet", "Pallet"),
+        ],
+        string="Type",
+    )