message: [Qt] Fix warning dialog popup for the Blockchain Explorer
  We have `txindex` enabled by default, but the check here was expecting
  it to be disabled by default so the warning dialog was being displayed
  informing users that they would need to enable a setting that was
  already enabled.
diff: @@ -472,7 +472,7 @@ void BlockExplorer::showEvent(QShowEvent*)
  m_History.push_back(text);
  updateNavButtons();
  - if (!GetBoolArg("-txindex", false)) {
  + if (!GetBoolArg("-txindex", true)) {
  QString Warning = tr("Not all transactions will be shown. To view all transactions you need to set txindex=1 in the configuration file (pivx.conf).");
  QMessageBox::warning(this, "PIVX Core Blockchain Explorer", Warning, QMessageBox::Ok);
  }
  