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
test PLAIN auth with failed login

This test fails because PLAIN authentication doesn't actually reject connections
test failed CURVE auth

adds expect_bounce_fail test function

which is like bounce, but fails if messages arrive.
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
Merge pull request #637 from minrk/test_plain_inauth

test failed auth for both PLAIN and CURVE
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