FX 5.1: USB OTG Support. UI Enhancements. Added range select in
file/media listings. Added "Select All" option in media listings.
Synthesized file listings (restores "System" catalog functionality
in Android 7 / N).
5.1.0.23 adds support for in-app purchase of Plus license key (IAP
/ Google Play Services NOT Required, APK license will remain
available). Android 7 API support.