[WIP] Issue 835 speech warnings

Settings have been implemented.  Now the features need to be implemented:

- [ ] Solar Activity Warning
- [ ] Wind Speed
- [x] 400ft ceiling exceeded
- [ ] low signal strength
- [x] lost signal
- [ ] low battery
@ne0fhyk But getSpokenStatusInterval() uses `prefs.getString()`, not `context.getString()`.  Which one should I use?