* [New] prepare bookcal DB for multicompany
Add entity to calendar and availability tables
* Fix propagate bookcal mods to main tables
add entity field for bookcal to install scripts (not only migration)
* add entity to bookcal_calendar only
as per requested, add entity to bookcal_calendar only
modified: htdocs/install/mysql/migration/19.0.0-20.0.0.sql
modified: htdocs/install/mysql/tables/llx_bookcal_calendar-bookcal.sql
* Revert changes on availabilities table