Rename LIGHT_COUNTER to DAY_PHASE for clarity
Use default set of calibration data rather than zeroing.

Using default data means that a fresh device at least starts out with a
reasonable set of calibration values allowing it to function at first
boot.
Minimise status strings to save memory.
Improve comments and layout
Allow zeroing goal and phase
Allow re-setting to the half day phase
Implementation of rolling history record

Track memory wrapping event so that the log can always be out put from
oldest to newest data available. E.g. a rolling history of 7 days
Removed a space from a status message
New display status format for machine readability.
Always send a display status as first part of a connection
Tidy up TODO comments.