Easy GPS logger

Invalid date

- Notification icon now shows an X if not logging (and text is slightly changed)
- Zoomed clock display now covers the start/stop buttons
- Updated app to latest Android version, with permission approval prompts
- Rare save errors now cause intentional crash (to report error)
Fixes:
- Crashed if you put other GPX files in app's folder
- Crashed if you clicked top icon to go back from Help screen
- Altitude display was incorrect (logged data was OK)
- Notification was updated too frequently