Allow relative torrent paths when qBittorrent is already running

Adding new torrents from the command line while qBittorrent was
already running was possible only providing the absolute path to
the file.

src/main.cpp

@@ -232,9 +232,14 @@ int main(int argc, char *argv[]) {
     QStringList torrentCmdLine = app.arguments();
     //Pass program parameters if any
     QString message;
+    QFileInfo torrentPath;
     for (int a = 1; a < torrentCmdLine.size(); ++a) {
       if (torrentCmdLine[a].startsWith("--")) continue;
-      message += torrentCmdLine[a];
+      torrentPath.setFile(torrentCmdLine[a]);
+      if (torrentPath.exists())
+        message += torrentPath.absoluteFilePath();
+      else
+        message += torrentCmdLine[a];
       if (a < argc-1)
         message += "|";
     }