Make HTML the default output format.  That is, make HTML the last format to catch output events and apply it to the catch-all accept header.

Issue #1180112 by franz, Pedro Lozano, amateescu: Move drupal_*_schema_*() functions into one place.

Issue #1471364 by amateescu: Move mail system classes from system.mail.inc to PSR-0 classes in Drupal\Core.

Revert "Issue #1089040 by Remon, mlncn: Added Cache rdf_get_namespaces() using drupal_static(). Don't add caches unless there's a demonstrated performance degradation."

This reverts commit 8d153441.

Issue #93854 by pillarsdotnet, Steven Jones, Dave Reid, ericduran, xjm, das-peter, et al: Fixed Allow autocompletion requests to include slashes.

Add a JSON response subscriber.  This is largely the same as the HTML one, but forces the appropriate mime type for responses.

Issue #1373142 by sun, beejeebus, aspilicious, amateescu: Use the Testing profile. Speed up testbot by 50%.

Add BC shiv to keep old-style Dirty URLs working.  This should be a temporary fix only, and be removed later.

- Patch #1216976 by cosmicdreams, DyanneNova, aspilicious, rupl, Jacine, mortendk, dcmouyard: clean up the CSS for Comment module.

- Patch #1216976 by cosmicdreams, DyanneNova, aspilicious, rupl, Jacine, mortendk, dcmouyard: clean up the CSS for Comment module.

- Patch #532512 by Gábor Hojtsy, andypost, no_commit_credit: fixed Plural string storage is broken, editing UI is missing.

This reverts commit de2ef9de.