the Ctrl-C signal handler on Windows

Patch by Serhiy Storchaka.

invalid parameters.

If messages were only added, a new file is no longer created and
renamed over the old file when flush() is called on an mbox, MMDF or
Babyl mailbox.

(helps getting results in real-time when stdio is transmitted over a pipe or socket)

They no longer lose data when an underlying read system call is interrupted.
IOError is no longer raised due to a read system call returning EINTR from
within these methods.

mktime() when timezone offest is supplied.

Loosely based on the work by Hirokazu Yamamoto.

Patch by Serhiy Storchaka.

Patch by Hallvard B Furuseth.

The tutorial had some outdated examples.  The patch also adds a caution
about the meaning of parens in the except statement.

Patch by Marien Zwart.