annogen Android apps: mode selector for sharpMulti + fix what happens if GOOGLE_PLAY_TRACK is set to empty string

Remove deprecated iOS browser app: the App Store stopped accepting UIWebView apps in April (updates are allowed till December but I think all existing annogen-influenced iOS apps use JS/Dart instead)

annogen Android apps: try to avoid other apps intercepting EPUB URL when we want it downloaded for annotation

option to power-cycle a router via home-control equipment (just Pi-mote for now), in case of router crash while you're asleep or something