Bug fixing

- isPlayerPrepared() illegalState bug fixed
- tag editor bug fixed when track number field is empty
- updated the tag editor track field hint

app/src/main/res/layout/activity_song_tag_editor.xml

@@ -169,7 +169,7 @@
                         android:layout_gravity="center"
                         android:fontFamily="sans-serif"
                         android:gravity="center_vertical"
-                        android:hint="@string/track"
+                        android:hint="@string/track_hint"
                         android:inputType="numberDecimal"
                         android:singleLine="true"
                         android:textAppearance="@style/TextAppearance.AppCompat.Title"

app/src/main/res/values/strings.xml

@@ -46,6 +46,7 @@
     <string name="album_artist">Album artist</string>
     <string name="year">Year</string>
     <string name="track">Track</string>
+    <string name="track_hint">Track (2 for track 2 or 3004 for CD3 track 4)</string>
     <string name="album_or_artist_empty">The album title or the album artist text field is empty.</string>
     <string name="writing_file_number">Writing file</string>
     <string name="title_activity_album_tag_editor">AlbumTagEditorActivity</string>