Given a graph and a node, determine if the node is a split code.
is_split(graph, node)TRUE if the node is split, otherwise FALSE.
A graph generated by klass_graph.
A node as returned by klass_node or
V.
The function will attempt to reconcile nodes that have split and
then later merged again. A node is considered to be split if there is more
than one node that does not itself have children (i.e. nodes at the end of
a sequence of changes) that can be reached from node