picklers: pylint cleanup

Signed-off-by: David Aguilar <davvid@gmail.com>
compat: readability tweaks

Signed-off-by: David Aguilar <davvid@gmail.com>
handlers: update the SimpleReduceHandler docstring

Signed-off-by: David Aguilar <davvid@gmail.com>
picklers: add support for Queue objects

Add a custom handler for serializing Queue objects.

Closes #74

Reported-by: dichotomy <dichotomy@riseup.net>
Signed-off-by: David Aguilar <davvid@gmail.com>