Remove delay options

These were exposed to users, but have subsequently been removed as
sockopts. They are currently only being used by ZAP, so I've moved it to
a simpl function call (actually it's only used in one case even in that,
so there may be a further simplification possible there).
Merge in master changes
fix type on HWM
add test_linger

tests that default LINGER (-1) ensures message delivery.

Note: it fails for large messages ( > 1MB, depending on the system).
Adding test showing failure to close socket/context in forked child
Terminate context in a child process of fork() to replace file descriptors to not interfere with parent process's context
test_fork: update test to verify communication between parent and child
Fix unused variable when using eventfd
cast rc to size_t for comparisons

avoids -Wall failures comparing int to uint
test_fork.cpp: adding missing headers for linux
Merge pull request #628 from ianbarber/master

Remove delay options
Merge pull request #640 from mattconnolly/fork

Adding ability for a context to be terminated in a forked child process
Merge pull request #639 from minrk/test_linger

add test_linger
Whitespace fixes
Fixed 'make check' failures

- Split off NULL security check from PLAIN
- Cleaned up test_linger code a little
- Got all tests to pass, added TODOs for outstanding issues
- Added ZAP authentication for NULL test case
- NULL mechanism was not passing server identity - fixed
- cleaned up test_security_plain and removed option double-checks (made code ugly)
- lowered timeout on expect_bounce_fail to 150 msec to speed up checks
- removed all sleeps from test_fork and simplified code (it still passes :-)
Merge pull request #641 from hintjens/master

Fixed regression tests
Fixed ZAP authentication

- if ZAP server returns anything except 200, connection is closed
- all security tests now pass correctly
- test_security_curve now does proper client key authentication using test key
- test_security_plain now does proper password authentication
Merge pull request #642 from hintjens/master

Fixed ZAP authentication
Fix cmake file for security tests
Merge pull request #643 from ricnewton/master

Fix cmake file for security tests