Documentation: add a pointer to hosts(5) and services(5)
for symbolic host and port syntax. File: proto/master.

Bugfix (introduced: Postfix 3.0): the SMTP daemon did not
reset a previous session's command counts before rejecting
a client that exceeds request or concurrency rates. File:
smtpd/smtpd.c.

Feature: preserve the new file mtimes when installing
Postfix.  Ond_ej Lyson_k. Wietse made this conditional on
the presence of a new -keep-new-mtime flag. File: postfix-install.

Bugfix: unionmap did not propagate table lookup errors.
Based on patch by Roel van Meer. Files: util/dict_union.c,
util/dict_union_test.*.

Cleanup: added unit test for pipemap. Files: util/dict_pipe.c,
util/dict_pipe_test.*.

Documentation: added a note about the order of search
patterns and table lookup order. Files: proto/canonical,
proto/generic, proto/virtual.