To be done after 1.13-stable is branched.

Scan the codebase for deprecations marked with a 1.14 deadline and remove them (ack deprecation.*1.14). All deprecations with a 1.14 deadline have been shipped (at least) in 1.12 and 1.13.

Marked for a 1.13.0 release so it's done at the time of 1.13-stable branching, but please move to 1.14.0 when done.