Add 'is null'/'is not null' to user roles filter with a good description

Add an Output format for field: Comment: Approved and field: User: Active

Revert "#1199328 by casey, bojanz: Add typehintings to every place which doesn't break the api. KUDOS"

This reverts commit 553f0e80.

#1301790 by rfay, dereine: Use created instead of timestamp for user.created field, and add some move definition

#1251052 by dereine: Add automatic conversions of joins to relationships for users_roles and role. Additional clean up comment/node author relationship

#1270982 by drunken monkey, dereine: Allow to specify entity type on non-base-tables, which allows some fancy views integrations like a generic entity views integration

Issue #470258 by joachim after more than a year of work: Groupwise representative relationships. Or subquery relationships.