+- support NIL and strings where they are alternatives to literals
+- Debian Bug #531589: fetchmail ignores SIGUSR1 in idle mode.
+ seems non-trivial to fix: in imap_idle(), we wait for untagged
+ responses, and may be deep in SSL_peek -- and that restarts the
+ underlying blocking read() from the socket, so we never break out of
+ the SSL_peek() with SIGUSR1.
+- add repoll for all kinds of auth failures
+ (requires framework to track which auth failed in auto mode)
+- SockOpen sometimes exits with errno == 0, confusing users (found with
+ Google RealTime on Twitter)