[IMP] hr_expense: improve activity management on expense sheet model

This commit improves expense flow management through a better integration
of activities and addition of automated activities. Several things are done
in this commit :

 * expense sheet (report) model do not inherit from mail.activity.mixin.
   This commit adds the inherit so that expense users and managers can now
   schedule and manage activities on expense reports. This will help them
   in their daily job;
 * automatic activities generation is added for expense reports. Activities
   are generated for approval. They are also automatically set as done when
   validating or unlinked when refusing or resetting to avoid bloating users
   with unnecessary activities;
 * a menu to configure activity types is added. Indeed HR managers should be
   able to see and configure activity types related to their job;
 * filters are added to be able to use the systray and to filter the kanban
   view based on activities

Having automated activities allow to replace some messages and tracking
that were implemented to warn people of expense reports to approve.
This commit therefore

 * simplifies the tracking as tracking to confirm reports is not necessary
   anymore;
 * removes to approve subtype on report model as well as its parent subtype
   on the department. This allows to simplify chatter in hr_expense app;

1 files changed, 7 insertions, 16 deletions

diff --git a/addons/hr_expense/data/mail_data.xml b/addons/hr_expense/data/mail_data.xml
index be825bac3db..02d662ecff5 100644
--- a/addons/hr_expense/data/mail_data.xml
+++ b/addons/hr_expense/data/mail_data.xml
@@ -2,7 +2,13 @@
 <odoo>
     <data noupdate="1">
 
-        <!--default alias for leads-->
+        <record id="mail_act_expense_approval" model="mail.activity.type">
+            <field name="name">Expense Approval</field>
+            <field name="icon">fa-dollar</field>
+            <field name="res_model_id" ref="hr_expense.model_hr_expense_sheet"/>
+        </record>
+
+        <!-- default alias for expenses -->
         <record id="mail_alias_expense" model="mail.alias">
             <field name="alias_name">expense</field>
             <field name="alias_model_id" ref="model_hr_expense"/>
@@ -23,27 +29,12 @@
             <field name="default" eval="True"/>
             <field name="description">Expense report refused</field>
         </record>
-        <record id="mt_expense_confirmed" model="mail.message.subtype">
-            <field name="name">Submitted</field>
-            <field name="res_model">hr.expense.sheet</field>
-            <field name="description">Expense report submitted, waiting approval</field>
-            <field name="default" eval="True"/>
-        </record>
         <record id="mt_expense_paid" model="mail.message.subtype">
             <field name="name">Paid</field>
             <field name="res_model">hr.expense.sheet</field>
             <field name="description">Expense report paid</field>
             <field name="default" eval="False"/>
         </record>
-        <!-- Department (Parent) related subtypes for messaging / Chatter -->  
-        <record id="mt_department_expense_confirmed" model="mail.message.subtype"> 
-            <field name="name">Expenses To Approve</field> 
-            <field name="res_model">hr.department</field>  
-            <field name="default" eval="False"/>   
-            <field name="parent_id" eval="ref('mt_expense_confirmed')"/>   
-            <field name="relation_field">department_id</field> 
-            <field name="sequence" eval="10"/> 
-        </record>
 
         <!-- Email Templates -->
         <template id="hr_expense_template_refuse_reason">