main commit

Post-processing infrastructure
* remove interfaces with one implementation
* fix download resources with unknow length
* marquee style for ProgressDrawable
* "view details" option in mission context menu
* notification for finished downloads
* postprocessing infrastructure: sub-missions, circular file, layers for layers of abstractions for Java IO streams
* Mp4 muxing (only DASH brand)
* WebM muxing
* Captions downloading
* alert dialog for overwrite existing downloads finished or not.

Misc changes
* delete SQLiteDownloadDataSource.java
* delete DownloadMissionSQLiteHelper.java
* implement Localization from #114

Misc fixes (this branch)
* restore old mission listeners variables. Prevents registered listeners get de-referenced on low-end devices
* DownloadManagerService.checkForRunningMission() now return false if the mission has a error.
* use Intent.FLAG_ACTIVITY_NEW_TASK when launching an activity from gigaget threads (apparently it is required in old versions of android)

More changes
* proper error handling "infrastructure"
* queue instead of multiple downloads
* move serialized pending downloads (.giga files) to app data
* stop downloads when swicthing to mobile network (never works, see 2nd point)
* save the thread count for next downloads
* a lot of incoherences fixed
* delete DownloadManagerTest.java (too many changes to keep this file updated)

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

@@ -0,0 +1,66 @@
+package us.shandian.giga.get;
+
+import java.io.File;
+import java.io.Serializable;
+import java.text.SimpleDateFormat;
+import java.util.Calendar;
+
+public abstract class Mission implements Serializable {
+    private static final long serialVersionUID = 0L;// last bump: 5 october 2018
+
+    /**
+     * Source url of the resource
+     */
+    public String source;
+
+    /**
+     * Length of the current resource
+     */
+    public long length;
+
+    /**
+     * creation timestamp (and maybe unique identifier)
+     */
+    public long timestamp;
+
+    /**
+     * The filename
+     */
+    public String name;
+
+    /**
+     * The directory to store the download
+     */
+    public String location;
+
+    /**
+     * pre-defined content type
+     */
+    public char kind;
+
+    /**
+     * get the target file on the storage
+     *
+     * @return File object
+     */
+    public File getDownloadedFile() {
+        return new File(location, name);
+    }
+
+    public boolean delete() {
+        deleted = true;
+        return getDownloadedFile().delete();
+    }
+
+    /**
+     * Indicate if this mission is deleted whatever is stored
+     */
+    public transient boolean deleted = false;
+
+    @Override
+    public String toString() {
+        Calendar calendar = Calendar.getInstance();
+        calendar.setTimeInMillis(timestamp);
+        return "[" + calendar.getTime().toString() + "] " + location + File.separator + name;
+    }
+}