Random TraversalSource Selection in GremlinScriptEngine

GremlinScriptEngine implementations make a random TraversalSource selection when processing lambdas. Obviously it should be bound more clearly to the specific TraversalSource the caller requests. Another issue that isn't completely clear is that bindings passed from the client share the same namespace as TraversalSource bindings which means that if the TraversalSource is "g" then you couldn't write a traversal like: withSideEffect(“g”, “hello”). That could be smarter as well.