Now save files can be exported to ZIP / imported from ZIP by the option menu of the launcher activity.
This adds a minimal launcher activity for the android app, which does the followings: - Opens a file chooser to let user select a zip file - Extracts the zip into the app's internal storage - Launches the SDL activity
This just copies android-project/ directory of https://hg.libsdl.org/SDL/ (rev 13383) to android/.