Switch to ZMQ::FFI.
Bump version for temporary release.
ZMQ3 changes

- Remove SWAP, since libzmq3 removes it.
- Separate out HWM into sender and receiver.
Note: This probably needs implementing differently for backcompat.
First goal is simply to get 3 *working* though.
Added zmq_major_version accessor
Fix input.t for libzmq3.

Sleeping for 1 second isn't nice, but it's a test, and it's nearly definitely good enough.
Equally forking isn't great, but it's better than nothing.
Fix output.t for zmq3.

See last input.t commit message for more details.
Fix first message (probably) not sent with libzmq3
Fix pod coverage warnings on subs documented in roles.
Bump test release number.
Fix HWM handling in libzmq2.

Also de-gbjk the indentation.