Added a node dir to store home-made nodes. Added a batch_cloud_listener. First
iterations just listens for clouds and prints when they are received. Just for
testing that everything works.

Added .pyc files to gitignore

Took source for python_msg_conversions from fuerte distribution and copied
into nodes dir. Still needs to be tested.
Added a BatchCloudListener node that gets transforms and batch clouds, applies
the transform to the cloud, and prints some stuff out.
Added timing and a verbose option to BatchCloudListener.py
Changed tf lookup to match the other branch, which was working correctly.
Added a pyside-based point-cloud plotter to look at the model produced by the
batch_cloud_listener.py.