this commit allows specifying the group operator for each field. This functionality was originally included in a seperate module "bi_sql_editor_aggregate" in version 12.
* [IMP] is_materialized field non readonly on sql_valid state ; [FIX] block possibility to set indexes on non materialized view
* [FIX] set domain_force, group_ids readonly if state > sql_valid
* [IMP] better display of the field group_ids
* [IMP] possibility to reorder menu items from sql views
* [IMP] Do not warn user when setting sql view to draft if state is sql_valid
* [REF]
* [FIX] Set Date of the first execution in the action name
Fix error '... is not a table or foreign table'
Fix view (colors + oe_highlight)
Fix tests
Fix README + manifest
Fix back to draft
Fix cron call + default values
Use Postgres version 9.6 for travis builds
