Material dialog for PreferenceActivity

+ cleaning imports

vlc-android/src/org/videolan/vlc/gui/PreferencesActivity.java

@@ -22,7 +22,6 @@ package org.videolan.vlc.gui;
 
 import org.videolan.libvlc.HWDecoderUtil;
 import org.videolan.libvlc.LibVLC;
-import org.videolan.libvlc.LibVlcUtil;
 import org.videolan.vlc.MediaDatabase;
 import org.videolan.vlc.R;
 import org.videolan.vlc.audio.AudioService;
@@ -33,7 +32,6 @@ import org.videolan.vlc.util.BitmapCache;
 import org.videolan.vlc.util.Util;
 import org.videolan.vlc.util.VLCInstance;
 
-import android.app.AlertDialog;
 import android.app.Dialog;
 import android.content.Context;
 import android.content.DialogInterface;
@@ -53,6 +51,7 @@ import android.preference.PreferenceActivity;
 import android.preference.PreferenceGroup;
 import android.preference.PreferenceManager;
 import android.preference.PreferenceScreen;
+import android.support.v7.app.AlertDialog;
 import android.support.v7.widget.Toolbar;
 import android.util.TypedValue;
 import android.view.LayoutInflater;

vlc-android/src/org/videolan/vlc/gui/audio/AudioAlbumFragment.java

@@ -24,8 +24,6 @@
 package org.videolan.vlc.gui.audio;
 
 import android.annotation.TargetApi;
-import android.app.Activity;
-import android.app.AlertDialog;
 import android.graphics.Bitmap;
 import android.os.Build;
 import android.os.Bundle;
@@ -43,7 +41,6 @@ import android.view.View;
 import android.view.ViewGroup;
 import android.widget.AdapterView;
 import android.widget.AdapterView.AdapterContextMenuInfo;
-import android.widget.ExpandableListView;
 import android.widget.ImageView;
 import android.widget.ListView;
 
@@ -52,13 +49,9 @@ import org.videolan.vlc.MediaLibrary;
 import org.videolan.vlc.MediaWrapper;
 import org.videolan.vlc.R;
 import org.videolan.vlc.audio.AudioServiceController;
-import org.videolan.vlc.gui.CommonDialogs;
 import org.videolan.vlc.util.AndroidDevices;
-import org.videolan.vlc.util.VLCRunnable;
 
 import java.util.ArrayList;
-import java.util.Collections;
-import java.util.List;
 
 public class AudioAlbumFragment extends Fragment implements AdapterView.OnItemClickListener, View.OnClickListener {