Add ability to sort library by date added (closes #1287)

(cherry picked from commit 1813dbbf59)

# Conflicts:
#	app/build.gradle
#	app/src/main/java/eu/kanade/tachiyomi/data/database/DbOpenCallback.kt
#	app/src/main/java/eu/kanade/tachiyomi/ui/browse/migration/search/SearchPresenter.kt
#	app/src/main/java/eu/kanade/tachiyomi/ui/browse/source/browse/BrowseSourcePresenter.kt
#	app/src/main/java/eu/kanade/tachiyomi/ui/library/LibraryPresenter.kt
#	app/src/main/java/eu/kanade/tachiyomi/ui/library/LibrarySettingsSheet.kt
#	app/src/main/java/eu/kanade/tachiyomi/ui/library/LibrarySort.kt
#	app/src/main/java/eu/kanade/tachiyomi/ui/manga/chapter/ChaptersPresenter.kt

app/src/main/java/exh/GalleryAdder.kt

@@ -8,6 +8,7 @@ import eu.kanade.tachiyomi.source.SourceManager
 import eu.kanade.tachiyomi.source.online.UrlImportableSource
 import eu.kanade.tachiyomi.source.online.all.EHentai
 import eu.kanade.tachiyomi.util.chapter.syncChaptersWithSource
+import java.util.Date
 import uy.kohesive.injekt.injectLazy
 
 class GalleryAdder {
@@ -93,7 +94,10 @@ class GalleryAdder {
             manga.copyFrom(newManga)
             manga.initialized = true
 
-            if (fav) manga.favorite = true
+            if (fav) {
+                manga.favorite = true
+                manga.date_added = Date().time
+            }
 
             db.insertManga(manga).executeAsBlocking()