[IMP] sale_contract: recurring view refactoring, new fields and unit of measure

- add contract_type field on account.analytic.account and real_quantity on account.analytic.invoice.line
- refactor contract form and list views for better clarity (hide unnecessary fields depending on the type of contract)
- divide account_analityc_account class according to contract type for future work
- divide contract template menu in 3 menus depending on contract_type
- add on_change_uom behaviour on account recurring lines
- rewrite tests in python
- add new report (pivot & graph)
- end date of contract is now computed from the template recurring rules
- small fixes & usability improvements

addons/analytic_user_function/analytic_user_function_view.xml

@@ -39,7 +39,7 @@
             <field name="inherit_id" ref="analytic.view_account_analytic_account_form"/>
             <field name="arch" type="xml">
                 <separator name="description" position="before">
-                    <div name="user_function_price" attrs="{'invisible': [('invoice_on_timesheets','=',False)]}">
+                    <div name="user_function_price" attrs="{'invisible': ['|',('invoice_on_timesheets','=',False),('contract_type','!=','regular')]}">
                         <separator string="Invoice Price Rate per User"/>
                         <p class="oe_grey oe_edit_only">
                             Define a specific service (e.g. Senior Consultant)