protected String getEdgeLabel(String label) {
		label = label.replace("\\", "\\\\");
		label = label.replace("\"", "\\\"");
		label = label.replace("\n", "\\\\n");
		label = label.replace("\r", "");
        return label;
    }
Fix edge strings so they print out in DOT properly;
 generate any gated predicates on edge too.
tool/src/org/antlr/v4/tool/DOTGenerator.java