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/res/values-bg/strings.xml

@@ -1,6 +1,4 @@
 <resources>
-    <string name="app_name">Tachiyomi</string>
-
     <string name="name">Име</string>
 
     <!-- Activities and fragments labels (toolbar title) -->

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

@@ -1,6 +1,4 @@
 <resources>
-    <string name="app_name">Tachiyomi</string>
-
     <string name="name">Nombre</string>
 
     <!-- Activities and fragments labels (toolbar title) -->

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

@@ -1,6 +1,4 @@
 <resources>
-    <string name="app_name">Tachiyomi</string>
-
     <string name="name">Nom</string>
 
     <!-- Activities and fragments labels (toolbar title) -->

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

@@ -1,6 +1,4 @@
 <resources>
-    <string name="app_name">Tachiyomi</string>
-
     <string name="name">Nome</string>
 
     <!-- Activities and fragments labels (toolbar title) -->

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

@@ -1,7 +1,5 @@
 <?xml version="1.0" encoding="utf-8"?>
 <resources>
-    <string name="app_name">Tachiyomi</string>
-
     <string name="name">Nome</string>
 
     <!-- Activities and fragments labels (toolbar title) -->

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

@@ -1,6 +1,5 @@
 <?xml version="1.0" encoding="utf-8"?>
 <resources>
-    <string name="app_name">Tachiyomi</string>
     <string name="action_add">Добавить</string>
     <string name="action_add_category">Добавить категорию</string>
     <string name="action_add_to_home_screen">Добавить на домашний экран</string>

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

@@ -1,5 +1,5 @@
 <resources>
-    <string name="app_name">Tachiyomi</string>
+    <string name="app_name" translatable="false">Tachiyomi</string>
 
     <string name="name">Name</string>
 
@@ -224,6 +224,7 @@
     <string name="select_source">Select a source</string>
     <string name="no_valid_sources">Please enable at least one valid source</string>
     <string name="no_more_results">No more results</string>
+    <string name="local_source">Local manga</string>
 
     <!-- Manga activity -->
     <string name="manga_not_in_db">This manga was removed from the database!</string>