Rewrote Backup (#650)

* Rewrote Backup

* Save automatic backups with datetime

* Minor improvements

* Remove suggested directories for backup and hardcoded strings. Rename JSON -> Backup

* Bugfix

* Fix tests

* Run restore inside a transaction, use external cache dir for log and other minor changes

app/src/main/java/eu/kanade/tachiyomi/widget/CustomLayoutPicker.kt

@@ -0,0 +1,33 @@
+package eu.kanade.tachiyomi.widget
+
+import android.support.v7.widget.RecyclerView
+import android.view.ViewGroup
+import com.nononsenseapps.filepicker.AbstractFilePickerFragment
+import com.nononsenseapps.filepicker.FilePickerActivity
+import com.nononsenseapps.filepicker.FilePickerFragment
+import com.nononsenseapps.filepicker.LogicHandler
+import eu.kanade.tachiyomi.R
+import eu.kanade.tachiyomi.util.inflate
+import java.io.File
+
+class CustomLayoutPickerActivity : FilePickerActivity() {
+
+    override fun getFragment(startPath: String?, mode: Int, allowMultiple: Boolean, allowCreateDir: Boolean):
+            AbstractFilePickerFragment<File> {
+        val fragment = CustomLayoutFilePickerFragment()
+        fragment.setArgs(startPath, mode, allowMultiple, allowCreateDir)
+        return fragment
+    }
+}
+
+class CustomLayoutFilePickerFragment : FilePickerFragment() {
+    override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): RecyclerView.ViewHolder {
+        when (viewType) {
+            LogicHandler.VIEWTYPE_DIR -> {
+                val view = parent.inflate(R.layout.listitem_dir)
+                return DirViewHolder(view)
+            }
+            else -> return super.onCreateViewHolder(parent, viewType)
+        }
+    }
+}