-Added bulk playlist creation and append.

-Added UI to create playlist from service player activity.
-Added state saving to playlist dialogs.
-Removed access to history activity on service player activity.
-Made StreamEntity serializable.

app/src/main/java/org/schabi/newpipe/database/Migrations.java

@@ -15,7 +15,7 @@ public class Migrations {
             /*
             * Unfortunately these queries must be hardcoded due to the possibility of
             * schema and names changing at a later date, thus invalidating the older migration
-            * scripts if names are not hardcoded.
+            * scripts if they are not hardcoded.
             * */
 
             // Not much we can do about this, since room doesn't create tables before migration.

app/src/main/java/org/schabi/newpipe/database/stream/model/StreamEntity.java

@@ -9,15 +9,18 @@ import android.arch.persistence.room.PrimaryKey;
 import org.schabi.newpipe.extractor.stream.StreamInfo;
 import org.schabi.newpipe.extractor.stream.StreamInfoItem;
 import org.schabi.newpipe.extractor.stream.StreamType;
+import org.schabi.newpipe.playlist.PlayQueueItem;
 import org.schabi.newpipe.util.Constants;
 
+import java.io.Serializable;
+
 import static org.schabi.newpipe.database.stream.model.StreamEntity.STREAM_SERVICE_ID;
 import static org.schabi.newpipe.database.stream.model.StreamEntity.STREAM_TABLE;
 import static org.schabi.newpipe.database.stream.model.StreamEntity.STREAM_URL;
 
 @Entity(tableName = STREAM_TABLE,
         indices = {@Index(value = {STREAM_SERVICE_ID, STREAM_URL}, unique = true)})
-public class StreamEntity {
+public class StreamEntity implements Serializable {
 
     final public static String STREAM_TABLE             = "streams";
     final public static String STREAM_ID                = "uid";
@@ -78,6 +81,12 @@ public class StreamEntity {
                 info.uploader_name, info.duration);
     }
 
+    @Ignore
+    public StreamEntity(final PlayQueueItem item) {
+        this(item.getServiceId(), item.getTitle(), item.getUrl(), item.getStreamType(),
+                item.getThumbnailUrl(), item.getUploader(), item.getDuration());
+    }
+
     @Ignore
     public StreamInfoItem toStreamInfoItem() throws IllegalArgumentException {
         StreamInfoItem item = new StreamInfoItem(