* Feat/Easy Days
* format
* add easy_days_percentages to deck_config
* configure Easy Days via table
* remove unused code
* add translatable strings & add default of easy days
* don't check easy_days_percentages when deserialize
* pass test::all_reserved_fields_are_removed
* consider next_day_at when interval_to_weekday
* remove y-axis-title created in last simulation
* EstimatedTotalKnowledge should be integer
* Reorder deck option sections (dae)
- Move FSRS to bottom left, to move it closer to the top, and so
the left and right columns appear roughly balanced when FSRS is
enabled.
- Move Easy Days above Advanced
* Don't crash if wrong number of days (dae)
* Use lower field number (dae)
Repeated fields are more compactly stored in the first 15 fields.
