Allow to remove a favorite manga from info tab

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

@@ -5,7 +5,14 @@
         android:id="@+id/action_favorite"
         android:title="@string/action_favorite"
         android:icon="@drawable/ic_action_favorite"
-        app:showAsAction="always"
-        android:visible="false"/>
+        android:visible="false"
+        app:showAsAction="ifRoom" />
+
+    <item
+        android:id="@+id/action_remove_favorite"
+        android:title="@string/action_remove_favorite"
+        android:icon="@drawable/ic_action_favorite_border"
+        android:visible="false"
+        app:showAsAction="ifRoom" />
 
 </menu>

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

@@ -70,8 +70,8 @@
     <string name="success">Success</string>
     <string name="invalid_login">Login error</string>
     <string name="loading">Loading…</string>
-    <string name="toast_added_favorites">Added to favorites</string>
-    <string name="action_favorite">Favorite</string>
+    <string name="action_favorite">Add to favorites</string>
+    <string name="action_remove_favorite">Remove from favorites</string>
     <string name="downloading">Downloading…</string>
     <string name="download_progress">Downloaded %1$d%%</string>
     <string name="chapter_progress">Page: %1$d</string>