hr_holidays_usability: add support for emails

Many small fixes and improvements

hr_holidays_usability/security/holiday_security.xml

@@ -1,5 +1,5 @@
 <?xml version="1.0" encoding="utf-8"?>
-<odoo noupdate="0">
+<odoo noupdate="1">
 
 <!--
 Employee : only see his holidays
@@ -40,4 +40,10 @@ Manager = person that administrates the holidays process : can see everything, d
     <field name="groups" eval="[(4, ref('hr_holidays.group_hr_holidays_manager'))]"/>
 </record>
 
+<record id="hr_holidays_multicompany_rule" model="ir.rule">
+    <field name="name">Holidays multi-company</field>
+    <field name="model_id" ref="hr_holidays.model_hr_holidays"/>
+    <field name="domain_force">['|', ('company_id', '=', False), ('company_id', 'child_of', [user.company_id.id])]</field>
+</record>
+
 </odoo>