Myfitnesspal-to-sqlite

- Fix: weight in the daily view now uses the average for a date rather than the sum.

- Fix `KeyError` when a measurement doesn't exist for a date.

- Create `daily` view with per-day analytics.
- Updates to `measurement_entries` table:
- Rename to `measurement_entry_items`.
- Replace `date` column with foreign key to `diary_entries`.
- Merge `measurements` CLI command into `diary` command. The rationale being that the tables are tightly coupled in any case, and that the new `daily` view depends on tables created in both commands.
- Remove `goal_` prefix from `goals` table columns.

- Initial release