Use a dialog fragment to select the import all type

MyTracks/res/menu/track_list.xml

@@ -30,14 +30,6 @@ limitations under the License.
     android:icon="@drawable/menu_import"
     android:id="@+id/track_list_import_all"
     android:title="@string/menu_import_all">
-    <menu>
-      <item
-        android:id="@+id/track_list_import_all_gpx"
-        android:title=""/>
-      <item
-        android:id="@+id/track_list_import_all_kml"
-        android:title=""/>
-    </menu>
   </item>
   <item
     android:icon="@drawable/menu_save"

MyTracks/res/values/strings.xml

@@ -844,6 +844,17 @@ limitations under the License.
       %1$s: the directory. E.g., '/storage/sdcard0/MyTracks/gpx/'.">
     Importing from %1$s…
   </string>
+  <string name="import_selection_option"
+    translation_description="When importing from external storage, the option to import all
+      files of a certain file format.
+
+      %1$s: file format. E.g., 'GPX'.">
+    Import all %1$s
+  </string>
+  <string name="import_selection_title"
+     translation_description="The dialog title when importing from external storage.">
+    Import from external storage
+  </string>
   <string name="import_success"
     translation_description="When importing from the external storage, the success message.
 
@@ -1016,15 +1027,7 @@ limitations under the License.
     translation_description="In the menu, to import all tracks from the external storage.
 
       Character limit: ~20 (1 line)">
-    Import all from external storage
-  </string>
-  <string name="menu_import_all_format"
-    translation_description="Under the import all menu option, the submenu option to import all
-      files of a certain file format.
-
-      %1$s: file format. E.g., 'GPX'.
-      Character limit: ~20 (1 line)">
-    Import %1$s
+    Import all
   </string>
   <string name="menu_insert_marker"
     translation_description="In the menu, to insert a marker.