Updating examples for Planet 2 package system
Update postface.txt

a typo
though --> through
Fix for subtree in clone.py
Fix incorrect variable name
Merge pull request #361 from kputnam/fix-typo

Fix incorrect variable name (Ch. 2)
Fixed old code usage
Updating code to work with Perl's ZMQ::LibZMQ3 module (up from
ZMQ::LibZMQ2).
Keeping this first example simple.
No need for this var anymore.
Updating the multi socket examples to work with ZMQ::LibZMQ3.
Updated the request-reply broker example to use ZMQ::LibZMQ3.
Trivial port of msgqueue example to use ZMQ::LibZMQ3
Upgrading the weather updates proxy example to use ZMQ::LibZMQ3.
Updating the parallel pipeline with KILL signal task vent-worker-sink
implementation to use ZMQ::LibZMQ3.
Updating the multithreaded server example to use ZMQ::LibZMQ3.
Updated multithreaded relay example to use ZMQ::LibZMQ3.
Updating the Pub-Sub Synchronization example to use the ZMQ::LibZMQ3 library
Updated the Pub-Sub Message Envelopes example to use ZMQ::LibZMQ3
Merge pull request #363 from nunonunes/Perl-ZMQ-LibZMQ3

Porting Perl examples to use ZMQ::LibZMQ3
Fixes some typos.