fix minor typo in zmq_ctx_get doc example
Merge pull request #693 from calid/doc-fix

fix minor typo in zmq_ctx_get doc example
Clarified that zmq.h constants are part of the public contract
Disabled randomly failing part of test
Merge pull request #694 from hintjens/master

Clarified that zmq.h constants are part of the public contract
Stop curve handshake when cookie box verification fails
replace macro constants with enum types for user facing constants
Merge pull request #695 from hurtonm/master

Stop curve handshake when cookie box verification fails
distinguish between options and defaults
Merge pull request #696 from calid/enum-constants

replace macro constants with enum types for user facing constants