fix Newick reader for named root vertex

Before this commit, the vtkNewickTreeReader would trash if you attempted
to load a file where the root vertex of the tree was named.

Change-Id: I1d1f282fc586a4a0b5569bb5d2e065dfe6a8aa7e

IO/Infovis/vtkNewickTreeReader.cxx

@@ -353,7 +353,7 @@ void vtkNewickTreeReader::CountNodes(char * const buffer, vtkIdType *numNodes)
     }
     else if (*current != ';' && *current != '\0')
     {
-      while (*current != ':')
+      while (*current != ':' && *(current+1) != ';' && *(current+1) != '\0')
       {
         current++;
       }