Implement Credential based default contract.

Provide new preference, which if set can be used to find portal global
contract document.

bt5/erp5_credential/PropertySheetTemplateItem/portal_property_sheets/CredentialPreference.xml

@@ -28,6 +28,10 @@
             <key> <string>id</string> </key>
             <value> <string>CredentialPreference</string> </value>
         </item>
+        <item>
+            <key> <string>last_id</string> </key>
+            <value> <string>1</string> </value>
+        </item>
         <item>
             <key> <string>portal_type</string> </key>
             <value> <string>Property Sheet</string> </value>

bt5/erp5_credential/PropertySheetTemplateItem/portal_property_sheets/CredentialPreference/preferred_credential_contract_document_reference_property.xml

+<?xml version="1.0"?>
+<ZopeData>
+  <record id="1" aka="AAAAAAAAAAE=">
+    <pickle>
+      <global name="Standard Property" module="erp5.portal_type"/>
+    </pickle>
+    <pickle>
+      <dictionary>
+        <item>
+            <key> <string>_local_properties</string> </key>
+            <value>
+              <tuple>
+                <dictionary>
+                  <item>
+                      <key> <string>id</string> </key>
+                      <value> <string>mode</string> </value>
+                  </item>
+                  <item>
+                      <key> <string>type</string> </key>
+                      <value> <string>string</string> </value>
+                  </item>
+                </dictionary>
+              </tuple>
+            </value>
+        </item>
+        <item>
+            <key> <string>categories</string> </key>
+            <value>
+              <tuple>
+                <string>elementary_type/string</string>
+              </tuple>
+            </value>
+        </item>
+        <item>
+            <key> <string>description</string> </key>
+            <value> <string>Reference of default contract document.</string> </value>
+        </item>
+        <item>
+            <key> <string>id</string> </key>
+            <value> <string>preferred_credential_contract_document_reference_property</string> </value>
+        </item>
+        <item>
+            <key> <string>mode</string> </key>
+            <value> <string></string> </value>
+        </item>
+        <item>
+            <key> <string>portal_type</string> </key>
+            <value> <string>Standard Property</string> </value>
+        </item>
+        <item>
+            <key> <string>preference</string> </key>
+            <value> <int>1</int> </value>
+        </item>
+        <item>
+            <key> <string>property_default</string> </key>
+            <value>
+              <none/>
+            </value>
+        </item>
+        <item>
+            <key> <string>write_permission</string> </key>
+            <value> <string>Manage properties</string> </value>
+        </item>
+      </dictionary>
+    </pickle>
+  </record>
+</ZopeData>

bt5/erp5_credential/SkinTemplateItem/portal_skins/erp5_credential/SystemPreference_viewCredential.xml

@@ -89,6 +89,7 @@
                         <string>my_preferred_credential_assignment_duration</string>
                         <string>my_preferred_login_and_password_notifier</string>
                         <string>my_preferred_subscription_assignment_category_list</string>
+                        <string>my_preferred_credential_contract_document_reference</string>
                       </list>
                     </value>
                 </item>

bt5/erp5_credential/bt/revision

-370
\ No newline at end of file
+371
\ No newline at end of file