[migration/3.18] disable all hooks when setting up symmetric relations This operation is semantically a no-op, so it should be invisible for the application. Related to #3259713.

[devtools] bases for instrumenting / debugging standard propagation hooks * a class that helps writing command to check propagation, detecting standard errors and picture the propagation as a graph * a class to instrument sets used to configure standard propagation hooks closes #3171980

instrument cwvreg, so we may know what's being loaded by asking the registry store

set proper PACKAGE information for yams 0.39 Yams 0.39 adds an unobstrusive API to get the package, or cube, defining a part of the schema (entity type, relation type/def). As CubicWeb overrides part of the schema reading process, we have to handle this information on our side so it will be properly set.

[yams] follow yams 0.39 api change introduced by ad95fd2c46de (package attribute on etype/rtype/rdef)

Make the GROUP_CONCAT aggregate function not repeat values (closes #3223975) Work on sets instead of arrays, so if the same value appears twice it's not repeated in the concatenated output. This patch handles the postgresql and sqlite backends, mysql is left alone at this point (seems doable, but I don't have time or motivation to fix and test it).

[mail] allow to specify SMTP's MAIL FROM address to config.sendmails(). Closes #3373620 Also modify testlib.Email so we don't loose this information and may test it.

[mail] format_mail copy/paste fix: we want to test sender-name, not sender-addr