New implementation of the MUS player (InfinityAmp)

Features:
- More playback controls (jump to previous or next title, play, pause, stop)
- Playback options: Loop, Shuffle
- Supports playback of music files from all games at once
- Refreshing or opening another game does not reset music player content
- Improved display of playlist entries and current playback time
- Sound filter to allow auto-skipping silent sound segments
- Music entries and player configuration is saved in NI's preferences
- Options for importing or exporting playlists (*.m3u or *.m3u8)
- Supports extended keyboard media keys for playback controls (Windows only)

Internal changes:
- Added StopWatch class
- Added InputKeyHelper class for extended virtual keys support (e.g. media keys)
- Extended ChildFrame class to allow persistent frames that survive refreshing
  and changing games

src/org/infinity/NearInfinity.java

@@ -687,6 +687,7 @@ public void actionPerformed(ActionEvent event) {
         statusBar.setMessage(msg);
         BrowserMenuBar.getInstance().gameLoaded(oldGame, oldFile);
         tree.setModel(treemodel);
+        ChildFrame.fireGameReset(false);
         containerpanel.removeAll();
         containerpanel.add(createJavaInfoPanel(), BorderLayout.CENTER);
         containerpanel.revalidate();
@@ -879,6 +880,7 @@ public void openGame(Path keyFile) {
       statusBar.setMessage(msg);
       BrowserMenuBar.getInstance().gameLoaded(oldGame, Objects.requireNonNull(oldKeyFile).toString());
       tree.setModel(treemodel);
+      ChildFrame.fireGameReset(false);
       containerpanel.removeAll();
       containerpanel.add(createJavaInfoPanel(), BorderLayout.CENTER);
       containerpanel.revalidate();
@@ -915,7 +917,7 @@ public void showResourceEntry(ResourceEntry resourceEntry, Operation doneOperati
 
   public void quit() {
     if (removeViewable()) {
-      ChildFrame.closeWindows();
+      ChildFrame.closeWindows(true);
       storePreferences();
       clearCache(false);
       System.exit(0);
@@ -944,6 +946,7 @@ public void refreshGame() {
         containerpanel.repaint();
       }
       cacheResourceIcons(true);
+      ChildFrame.fireGameReset(true);
     } finally {
       blocker.setBlocked(false);
     }

src/org/infinity/gui/ChildFrame.java

@@ -45,18 +45,34 @@ public class ChildFrame extends JFrame {
 
   private final boolean closeOnInvisible;
 
-  /** Closes all child windows. */
+  // Indicates whether the window should be closed when the game is reset or closed
+  private boolean closeOnReset;
+
+  /** Closes all child windows except for child windows with {@code closeOnReset} set to {@code false}. */
   public static int closeWindows() {
-    return closeWindow((Class<ChildFrame>)null);
+    return closeWindow((Class<ChildFrame>)null, false);
   }
 
-  /** Closes all windows of the specified window class. */
+  /** Closes all child windows. */
+  public static int closeWindows(boolean forced) {
+    return closeWindow((Class<ChildFrame>)null, forced);
+  }
+
+  /**
+   * Closes all windows of the specified window class except for child windows with {@code closeOnReset} set to
+   * {@code false}.
+   */
   public static int closeWindow(Class<ChildFrame> frameClass) {
+    return closeWindow(frameClass, false);
+  }
+
+  /** Closes all windows of the specified window class. */
+  public static int closeWindow(Class<ChildFrame> frameClass, boolean forced) {
     int retVal = 0;
     WindowEvent event = new WindowEvent(NearInfinity.getInstance(), WindowEvent.WINDOW_CLOSING);
     for (Iterator<ChildFrame> i = WINDOWS.iterator(); i.hasNext();) {
       ChildFrame frame = i.next();
-      if (frameClass == null || frame.getClass() == frameClass) {
+      if ((forced || frame.isCloseOnReset()) && (frameClass == null || frame.getClass() == frameClass)) {
         i.remove();
         retVal++;
         closeWindow(frame, event);
@@ -77,6 +93,31 @@ public static boolean closeWindow(ChildFrame frame) {
     return retVal;
   }
 
+  /**
+   * Signals all persistent {@link ChildFrame} instances that the game has been refreshed or a new game has been opened.
+   *
+   * @param refreshOnly Specify {@code true} if the game has only been refreshed.
+   */
+  public static void fireGameReset(boolean refreshOnly) {
+    fireGameReset(null, refreshOnly);
+  }
+
+  /**
+   * Signals all persistent {@link ChildFrame} instances of the given class that the game has been refreshed or a new
+   * game has been opened.
+   *
+   * @param frameClass  Filter by the specific {@code ChildFrame} class. Specify {@code null} to process all instances.
+   * @param refreshOnly Specify {@code true} if the game has only been refreshed.
+   */
+  public static void fireGameReset(Class<ChildFrame> frameClass, boolean refreshOnly) {
+    for (Iterator<ChildFrame> iter = WINDOWS.iterator(); iter.hasNext(); ) {
+      final ChildFrame frame = iter.next();
+      if (!frame.isCloseOnReset() && (frameClass == null || frame.getClass() == frameClass)) {
+        frame.gameReset(refreshOnly);
+      }
+    }
+  }
+
   /**
    * Returns first window with specified class or {@code null} if such window do not exist.
    *
@@ -170,10 +211,14 @@ public static void updateWindowGUIs() {
   }
 
   protected ChildFrame(String title) {
-    this(title, false);
+    this(title, false, true);
   }
 
   public ChildFrame(String title, boolean closeOnInvisible) {
+    this(title, closeOnInvisible, true);
+  }
+
+  public ChildFrame(String title, boolean closeOnInvisible, boolean closeOnReset) {
     super(title);
     setIconImages(NearInfinity.getInstance().getIconImages());
     this.closeOnInvisible = closeOnInvisible;
@@ -222,6 +267,33 @@ public void close() {
     WINDOWS.remove(this);
   }
 
+  /**
+   * Returns whether the {@code ChildFrame} instance is automatically closed when the game is refreshed or closed.
+   *
+   * @return {@code true} if the frame is closed automatically if the game state changes, {@code false} otherwise.
+   */
+  public boolean isCloseOnReset() {
+    return closeOnReset;
+  }
+
+  /**
+   * Specifies whether the {@code ChildFrame} instance is automatically closed when the game is refreshed or closed.
+   *
+   * @param b Specify whether to close the frame automatically if the game state changes.
+   */
+  public void setCloseOnReset(boolean b) {
+    closeOnReset = b;
+  }
+
+  /**
+   * This method is called whenever the game has been refreshed or a new game has been opened. It is only relevant for
+   * frames that persist after refreshing or reopening games, i.e. when {@link #isCloseOnReset()} returns {@code false}.
+   *
+   * @param refreshOnly {@code true} if the game content has only been refreshed.
+   */
+  protected void gameReset(boolean refreshOnly) {
+  }
+
   /**
    * This method is called whenever the dialog is about to be closed and removed from memory.
    *

src/org/infinity/gui/InfinityAmp.java

@@ -42,6 +42,7 @@
 import org.infinity.util.SimpleListModel;
 import org.infinity.util.io.StreamUtils;
 
+@Deprecated
 public final class InfinityAmp extends ChildFrame
     implements ActionListener, ListSelectionListener, Runnable, Closeable {
   private final SimpleListModel<ResourceEntry> allMusModel = new SimpleListModel<>();