Open from homescreen/add shortcut to launcher (#435)

* Add very basic "Add to homescreen" action in manga info fragment.

* Fix open from homescreen opening current manga (if a manga is open).
Code cleanup.

* Improve fix for "Opening from homescreen opens currently open manga if a manga is currently open" and fix "Going back to the main app via a Manga opened through a shortcut repeats the launcher open animation".

* Implement custom icons, add star icon and optimize some things.

* Remove Tachiyomi and custom image icon types.

* Move icon creation task into an observable.
Added some extra error handling.

app/src/main/res/drawable/ic_home_white_24dp.xml

@@ -0,0 +1,9 @@
+<vector xmlns:android="http://schemas.android.com/apk/res/android"
+        android:width="24dp"
+        android:height="24dp"
+        android:viewportWidth="24.0"
+        android:viewportHeight="24.0">
+    <path
+        android:fillColor="#ffffff"
+        android:pathData="M10,20v-6h4v6h5v-8h3L12,3 2,12h3v8z"/>
+</vector>

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

@@ -12,4 +12,8 @@
         android:title="@string/action_open_in_browser"
         app:showAsAction="never"/>
 
+    <item android:id="@+id/action_add_to_home_screen"
+        android:title="@string/action_add_to_home_screen"
+        app:showAsAction="never"/>
+
 </menu>

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

@@ -51,6 +51,7 @@
     <string name="action_remove">Remove</string>
     <string name="action_resume">Resume</string>
     <string name="action_open_in_browser">Open in browser</string>
+    <string name="action_add_to_home_screen">Add to home screen</string>
     <string name="action_display_mode">Change display mode</string>
     <string name="action_set_filter">Set filter</string>
     <string name="action_cancel">Cancel</string>
@@ -225,6 +226,16 @@
     <string name="manga_info_genres_label">Genres</string>
     <string name="share_subject">Share…</string>
     <string name="share_text">Check out %1$s! at %2$s</string>
+    <string name="added_to_home_screen">Manga added to home screen</string>
+    <string name="icon_type">Icon type</string>
+    <string name="tachiyomi_icon">Tachiyomi icon</string>
+    <string name="circular_icon">Circular icon</string>
+    <string name="rounded_icon">Rounded icon</string>
+    <string name="square_icon">Square icon</string>
+    <string name="star_icon">Star icon</string>
+    <string name="shortcut_title">Shortcut title</string>
+    <string name="icon_shape">Icon shape</string>
+    <string name="icon_creation_fail">Failed to create shortcut!</string>
 
     <!-- Manga chapters fragment -->
     <string name="manga_chapters_tab">Chapters</string>
@@ -305,6 +316,7 @@
     <!-- File Picker Titles -->
     <string name="file_select_cover">Select cover image</string>
     <string name="file_select_backup">Select backup file</string>
+    <string name="file_select_icon">Select shortcut icon</string>
 
     <!--UpdateCheck-->
     <string name="update_check_title">New update available!</string>