discoveryserver change default value (server) and minor fix in subst_column_macros

Former-commit-id: ff22af353cf794ae0600a23d61fd30256193d463

pandora_server/lib/PandoraFMS/Config.pm

@@ -226,7 +226,7 @@ sub pandora_load_config {
 	$pa_config->{"dataserver"} = 1; # default
 	$pa_config->{"networkserver"} = 1; # default
 	$pa_config->{"snmpconsole"} = 1; # default
-	$pa_config->{"discoveryserver"} = 1; # default
+	$pa_config->{"discoveryserver"} = 0; # default
 	$pa_config->{"wmiserver"} = 1; # default
 	$pa_config->{"pluginserver"} = 1; # default
 	$pa_config->{"predictionserver"} = 1; # default

pandora_server/lib/PandoraFMS/Core.pm

@@ -3811,7 +3811,10 @@ sub subst_alert_macros ($$;$$$$) {
 ##########################################################################
 sub subst_column_macros ($$;$$$$) {
 	my ($string, $macros, $pa_config, $dbh, $agent, $module) = @_;
-	
+
+	# Avoid to manipulate null strings
+	return $string unless defined($string);	
+
 	# Do not attempt to substitute macros unless the string
 	# begins with an underscore.
 	return $string unless substr($string, 0, 1) eq '_';