MP4 muxer +misc modifications

* allow retry downloads with "post-processing failed" error in the new muxer
* MPEG-4 muxer  ¡¡ no DASH output!!
* keep the progress if download fails
* remove TODO in SecondaryStreamHelper.java
* misc clean-up
* delete TestAlgo.java
* delete ExtSDDownloadFailedActivity.java and remove it from AndroidManifest.xml
* use hardcored version for changing icon colors

app/src/main/java/us/shandian/giga/get/DownloadInitializer.java

@@ -156,7 +156,6 @@ public class DownloadInitializer extends Thread {
 
                 if (retryCount++ > mMission.maxRetry) {
                     Log.e(TAG, "initializer failed", e);
-                    mMission.running = false;
                     mMission.notifyError(e);
                     return;
                 }