This also drops the trailing period from the log message, which matches the
changes to core.

This enables race-free kicking using socket+SIGTERM.

Pass IP structure to URL API instead of only the hostname as a string.

managesieve-login: managesieve-proxy - Allow parsing AUTHENTICATE response codes other than TRYLATER.

Fixes argument list too long error.

This allows passing passdb variables. They are prefixed with forward_ when
imported to extra fields.

Upon login success, the next line was erroneously skipped.

Fixes:

Panic: file istream-crlf.c: line 24 (i_stream_crlf_read_common): assertion failed: (ret != -2)
Panic: file istream.h: line 228 (i_stream_read_more): assertion failed: (ret != -2)
(various other similar panics are possible)