1. Added more of the required logic to the Trend Log write property handler.
2. Fixed some mistakes in the read property handler
3. TrendLog_Init now sets up data to allow for testing.
4. Enabled write property handling in main.c
1. Added time to live functionality
2. Added option of partial cache init on reset to reduce traffic for controllers that can preserve RAM over power cycle/reset.
3. Can now put new entries in the cache even if it is full - entry nearest to expiry is dropped to make room.