even_graph: Class of graphs where all nodes have even degree
Description
This class is an extension of graphNEL-class. For graphs of this class, euler tours may always be constructed. Objects of this class should be created by mk_even_graph
% \item{\code{nodes}:}{Object of class \code{"vector"} ~~ }
% \item{\code{edgeL}:}{Object of class \code{"list"} ~~ }
% \item{\code{edgemode}:}{Object of class \code{"character"} ~~ }
% \item{\code{edgeData}:}{Object of class \code{"attrData"} ~~ }
% \item{\code{nodeData}:}{Object of class \code{"attrData"} ~~ }
% \item{\code{renderInfo}:}{Object of class \code{"renderInfo"} ~~ }
% \item{\code{graphData}:}{Object of class \code{"list"} ~~ }