taddr private keys can start with a 7

src/mainwindow.cpp

@@ -945,7 +945,7 @@ void MainWindow::doImport(QList<QString>* keys) {
 
     if (key.startsWith("secret")) {
         rpc->importZPrivKey(key, [=] (auto) { this->doImport(keys); });
-    } else if (key.startsWith("U") || key.startsWith("5") || key.startsWith("L") || key.startsWith("K")) {
+    } else if (key.startsWith("U") || key.startsWith("5") || key.startsWith("L") || key.startsWith("K") || key.startsWith("7")) {
         // 5 = uncompressed, len=51
         // LK= compressed,   len=52
         // TODO: verify exact length of (un)compressed