JRPN 16c Legacy

Invalid date

Fixes bug with saving configuration. Configuration is now stored in the app's directory, rather than external storage. The update to API 29 had the side effect of requiring external storage permission for that, which the app wasn't requesting.

Also contains fixes from version 1.1, which was only briefly released:
Fixes display of status lables ("f", "g", "C", ...).
Fixes occasional crash when power key used to close app.
Minor appearance tweaks.