Separated libpupil to standalone repository

Migrated to Kotlin 1.4

app/src/main/res/menu/gallery.xml

@@ -1,35 +0,0 @@
-<?xml version="1.0" encoding="utf-8"?>
-<!--
-  ~     Pupil, Hitomi.la viewer for Android
-  ~     Copyright (C) 2019  tom5079
-  ~
-  ~     This program is free software: you can redistribute it and/or modify
-  ~     it under the terms of the GNU General Public License as published by
-  ~     the Free Software Foundation, either version 3 of the License, or
-  ~     (at your option) any later version.
-  ~
-  ~     This program is distributed in the hope that it will be useful,
-  ~     but WITHOUT ANY WARRANTY; without even the implied warranty of
-  ~     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-  ~     GNU General Public License for more details.
-  ~
-  ~     You should have received a copy of the GNU General Public License
-  ~     along with this program.  If not, see <http://www.gnu.org/licenses/>.
-  -->
-
-<menu xmlns:android="http://schemas.android.com/apk/res/android"
-    xmlns:app="http://schemas.android.com/apk/res-auto">
-
-    <item
-        android:id="@+id/gallery_favorite"
-        android:icon="@drawable/ic_star_empty"
-        android:title=""
-        app:showAsAction="ifRoom"/>
-
-    <item
-        android:id="@+id/gallery_download"
-        android:icon="@drawable/ic_download"
-        android:title=""
-        app:showAsAction="always"/>
-
-</menu>

app/src/main/res/menu/main.xml

@@ -23,9 +23,7 @@
 	<item android:id="@+id/main_menu_thin"
 		android:title="@string/main_menu_thin"/>
 
-	<item
-		android:id="@+id/main_menu_sort"
-		android:title="@string/main_menu_sort">
+	<item android:title="@string/main_menu_sort">
 		<menu>
 			<group android:checkableBehavior="single">
 				<item android:id="@+id/main_menu_sort_newest"