Add setting flag to enable bool -> int config file load conversion

src/settings.cpp

@@ -409,6 +409,10 @@ size_t IntSettingDesc::ParseValue(const char *str) const
 	char *end;
 	size_t val = strtoul(str, &end, 0);
 	if (end == str) {
+		if (this->flags & SF_CONVERT_BOOL_TO_INT) {
+			if (strcmp(str, "true") == 0 || strcmp(str, "on") == 0) return 1;
+			if (strcmp(str, "false") == 0 || strcmp(str, "off") == 0) return 0;
+		}
 		ErrorMessageData msg(STR_CONFIG_ERROR, STR_CONFIG_ERROR_INVALID_VALUE);
 		msg.SetDParamStr(0, str);
 		msg.SetDParamStr(1, this->name);

src/settings_internal.h

@@ -35,6 +35,7 @@ enum SettingFlag : uint32 {
 	SF_GUI_VELOCITY            = 1 << 18, ///< setting value is a velocity
 	SF_GUI_ADVISE_DEFAULT      = 1 << 19, ///< Advise the user to leave this setting at its default value
 	SF_ENUM_PRE_CB_VALIDATE    = 1 << 20, ///< Call the pre_check callback for enum incoming value validation
+	SF_CONVERT_BOOL_TO_INT     = 1 << 21, ///< Accept a boolean value when loading an int-type setting from the config file
 };
 DECLARE_ENUM_AS_BIT_SET(SettingFlag)