Adding publish and subscribe atomic client examples

[embhorn]

New examples in examples/pub-sub

These can be used for quickly testing MQTT application or scripting.

By default, they connect to localhost. Specify a topic with -n ./examples/pub-sub/mqtt-sub -n '#'

./examples/pub-sub/mqtt-pub -n test -m "Hello world!"

Enable verbose example debug with -d

[embhorn]

Should there be a new test script for the pub-sub clients?

I hadn't considered this. These are really just subsets of the mqttclient example. They could be used for testing against the protocol.

[embhorn]

Fixed executable names in .gitignore

[embhorn]

All looks good and tests out. I notice these aren't being used yet. Are you planning to add some additional scripts to test using these?

Yes, that is the intention, to better enable functional testing using these clients.