Looking for a good app that lets me play back random mp3s or audiobook files that I might get in email, or from the web. It would need to remember playback position of the file so I can always go back and listen from the spot i left off. Also be able to handle iOS file system so I could, from iOS, copy .mp3 files form email or wherever into the app and store there. i mostly use Apple Podcasts. But don't want to use iTunes to get them there.