Merge pull request #403 from hintjens/master

Removed custom zframe API
Merge pull request #404 from hintjens/master

Updated AUTHORS from git log
Merge pull request #405 from hintjens/master

Bumped version for 2.2.0
Merge pull request #406 from hintjens/master

Updated man pages
Merge pull request #408 from hintjens/master

Test case for 407
mark functions with printf() semantics with GCC format attribute

This enables format string checks for CZMQ functions that take
variable number of arguments in a manner similar to printf().

It also adds a few casts for places where size_t is passed
to functions with printf like syntax. There is a modifier to allow
use of size_t (%zd) but it is not portable to all operating systems
and compilers.

Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
Merge pull request #402 from shemminger/master

mark functions with printf() semantics with GCC format attribute
Merge pull request #410 from hintjens/master

Fixed issue #407
Merge pull request #411 from fichtner/format_string_fix

fix clang errors
fix clang errors

error: format string is not a string literal (potentially insecure)
    [-Werror,-Wformat-security]

(follow up on ceb91d4bf9b01b7272c509a1c9674d217e2b2384)
fix #407 for real
Merge pull request #412 from fichtner/zbeacon_freebsd

fix #407 for real :D
Updated for RFC 35
zsockopts_test now returns void
Various source cleanups
Added sys/un.h
Updated AUTHORS list