mod_smacks: Split enable handling to stages, to allow easier SASL2 integration

util.stanza: Add add_error() to simplify adding error tags to existing stanzas Some fiddling is required now in error_reply() to ensure the cursor is in the same place as before this change (a lot of code apparently uses that feature).

mod_component: Require 'from' attribute on stanzas by default The old behaviour of falling back to the component domain when it is missing has been merged into the logic for the existing "validate_from_addresses" option (which is strict by default). ejabberd already rejects component stanzas with no 'from' (as the XEP requires), and this has led to compatibility issues for components that were seemingly working fine with Prosody.

mod_external_services: Update tools.ietf.org URL See bd9e006a7a74

doap: Update for XEP-0215 advancement to Stable No other changes to account for.

core.usermanager: Link to docs for new role API to make warning more actionable

mod_smacks: Split resumption into multiple stages, to simplify ISR integration This will allow us to return the success/failed as part of the SASL2 response, and *then* perform the stanza sync as a second step.

mod_s2s: Simplify conditionals since all sessions should have .host now

Merge 0.12->trunk

mod_s2s: Fix firing buffer drain events Fixes the same kind of issue as in 65563530375b but once and for all, while improving similarity between incoming and outgoing connections.