[task] allow negative intervals for add_looping_task (closes #2818280) Instead of rejecting values < 0 with a ValueError, we ignore tasks with a negative interval. This introduce a simple way to disable task from configuration.

[task] allow interval=0 for looping tasks There is valid usecase for perpetual running task.

[portable dump] skip virtual relations, they have no table associated. Closes #2841199

[test] fix skipIf import, currently failing if unittest2 is not there

[test] fix bad merge

merge with other default head

[ldap] an empty 'user-base-dn' disable the user importation process, The same semantic will be used for group. We start by using it for user for the sake of consistency.

drop commented print

[ldap] Major test refactoring Mostly fix tests (previous refactoring), but also refactor a bit the base class to have better/simpler interaction with the slapd server.

[test/ldap] have RQL2LDAPFilterTC use its own database I do not know what RQL2LDAPFilterTC is about and why it does this strange reuse of LDAPUserSourceTC pre_setup_database but it is certainly a good idea to have it use a dedicated database-cache.

[ldap] quieter tests Capture slapadd and slapd output if everything goes well.

[test/ldap source] better source naming, some cleanups (prepares #2528116) ldap uri becomes "ldap" in all cases prepare separation of CONFIGs by source type

use cw_etype instead of __regid__ We have a clean public API now.

[entity] add an official ``cw_etype`` property for entity This property holds the CWEtype id of the entity. This information was previously available through __regid__ but this is an ugly public API. So we have a new clean public API. The ``dc_type()`` method could not be used as it is translated. (closes #2793792)

[notification] use new style operation for notification This results in far less operations created. Operation creation is expensive. We keep some compatibility with the previous API because some cubes have been reported to use it.