Persist library dialog state between invocations

app/src/main/java/com/kabouzeid/gramophone/model/CategoryInfo.java

@@ -1,8 +1,11 @@
 package com.kabouzeid.gramophone.model;
 
+import android.os.Parcel;
+import android.os.Parcelable;
+
 import com.kabouzeid.gramophone.R;
 
-public class CategoryInfo {
+public class CategoryInfo implements Parcelable {
     public Category category;
     public boolean visible;
 
@@ -11,6 +14,32 @@ public class CategoryInfo {
         this.visible = visible;
     }
 
+    public CategoryInfo(Parcel source) {
+        category = (Category) source.readSerializable();
+        visible = source.readInt() == 1 ? true : false;
+    }
+
+
+    @Override
+    public int describeContents() {
+        return 0;
+    }
+
+    public void writeToParcel(Parcel dest, int flags) {
+        dest.writeSerializable(category);
+        dest.writeInt(visible ? 1 : 0);
+    }
+
+    public static final Parcelable.Creator<CategoryInfo> CREATOR = new Parcelable.Creator<CategoryInfo>() {
+        public CategoryInfo createFromParcel(Parcel source) {
+            return new CategoryInfo(source);
+        }
+
+        public CategoryInfo[] newArray(int size) {
+            return new CategoryInfo[size];
+        }
+    };
+
     public enum Category {
         SONGS(R.string.songs),
         ALBUMS(R.string.albums),