message: core: fix the check for too long params
  Param names can be 16 chars at most (plus zero termination).
diff: @@ -38,7 +38,7 @@ void MAVLinkParameters::set_param_async(const std::string &name,
  // LogDebug() << "setting param " << name << " to " << value.get_int();
  // }
  - if (name.size() > PARAM_ID_LEN) {
  + if (name.size() >= PARAM_ID_LEN) {
  LogErr() << "Error: param name too long";
  if (callback) {
  callback(false);
  @@ -72,7 +72,7 @@ void MAVLinkParameters::get_param_async(const std::string &name,
  {
  // LogDebug() << "getting param " << name << ", extended: " << (extended ? "yes" : "no");
  - if (name.size() > PARAM_ID_LEN) {
  + if (name.size() >= PARAM_ID_LEN) {
  LogErr() << "Error: param name too long";
  if (callback) {
  ParamValue empty_param;
  