[5039] Changes after review:

- address_family_, default ctor removed from two parsers
 - copyright year updated
 - Element::getNonConst is now documented
 - user's guide is now clear about csv-format default value is now true

src/bin/dhcp4/json_config_parser.cc

@@ -575,7 +575,7 @@ configureDhcp4Server(Dhcpv4Srv&, isc::data::ConstElementPtr config_set) {
         // We need definitions first
         ConstElementPtr option_defs = mutable_cfg->get("option-def");
         if (option_defs) {
-            OptionDefListParser parser(AF_INET);
+            OptionDefListParser parser;
             CfgOptionDefPtr cfg_option_def = CfgMgr::instance().getStagingCfg()->getCfgOptionDef();
             parser.parse(cfg_option_def, option_defs);
         }