Fix searching for TDF file when url has a query string

* Correctly append ".tdf" to a url when there is a query string
* Fixes #1168

src/main/java/org/broad/igv/track/TrackLoader.java

@@ -952,7 +952,7 @@ private void loadAlignmentsTrack(ResourceLocator locator, List<Track> newTracks,
                                 path.contains("dataformat=.bam") ||
                                 path.contains("/query.cgi?");
                 if (!bypassFileAutoDiscovery) {
-                    covPath = path + ".tdf";
+                    covPath = ResourceLocator.appendToPath(locator, ".tdf");
                 }
             }