Local manga in zip/cbz/folder format (#648)

* add local source

* small fixes

* change Chapter to SChapter and and Manga to SManga in ChapterRecognition.
Use ChapterRecognition.parseChapterNumber() to recognize chapter numbers.

* use thread poll

* update isImage()

* add isImage() function to DiskUtil

* improve cover handling

* Support external SD cards

* use R.string.app_name as root folder name

app/src/main/java/eu/kanade/tachiyomi/ui/library/LibraryPresenter.kt

@@ -13,6 +13,7 @@ import eu.kanade.tachiyomi.data.database.models.MangaCategory
 import eu.kanade.tachiyomi.data.download.DownloadManager
 import eu.kanade.tachiyomi.data.preference.PreferencesHelper
 import eu.kanade.tachiyomi.data.preference.getOrDefault
+import eu.kanade.tachiyomi.source.LocalSource
 import eu.kanade.tachiyomi.source.SourceManager
 import eu.kanade.tachiyomi.ui.base.presenter.BasePresenter
 import eu.kanade.tachiyomi.util.combineLatest
@@ -345,6 +346,11 @@ class LibraryPresenter : BasePresenter<LibraryFragment>() {
      */
     @Throws(IOException::class)
     fun editCoverWithStream(inputStream: InputStream, manga: Manga): Boolean {
+        if (manga.source == LocalSource.ID) {
+            LocalSource.updateCover(context, manga, inputStream)
+            return true
+        }
+
         if (manga.thumbnail_url != null && manga.favorite) {
             coverCache.copyToCache(manga.thumbnail_url!!, inputStream)
             return true