Elkm1

- Lint cleanup
- Constants now all uppercase with underscores (can use pretty_const to print)
- Added encode for az, decode for AZ (no handler yet)

Fix syntax; more descriptive docstrings

- Make elk attribute in Element private
- Allow separator in default_name() to be specified
- Add constants for arming, alarms

- Add elk attribute to Element

- Add NS, NZ to no plans to implement list
- Make default name 1-based
- Add helpers to Output
- Add helpers to Light
- Add helper to Counter
- Add helper to Task
- Add helpers to Area
- Add handler for task change (TC) message
- Add thermostat setting
- Add helper for Setting (custom value)
- Added const for thermostat setting
- Added pretty_const (see test_util.py for API)

- Add display message encoder