This commit removes the String() method from the FeatureVector as it
can produce confusing output when revving a feature vector and not
knowing the strip mapping ahead of time.
'init' message is the first message reveals the features supported or required
by this node. Nodes wait for receipt of the other's features to simplify error
diagnosis where features are incompatible. This message will help negotioate the
the features which are supported by both sides.
