Base Concurrency

Module to regroup all workarounds/fixes to avoid concurrency issues in SQL.

• res.users login_date:

the login date is now separated from res.users; on long transactions, "re-logging" by opening a new tab changes the current res.user row, which creates concurrency issues with PostgreSQL in the first transaction.

This creates a new table and a function field to avoid this. In order to avoid breaking modules which access via SQL the login_date column, a cron (inactive by default) can be used to sync data.