hygiene, update copyright years
Merge branch 'code/hygiene'

* code/hygiene:
  hygiene, update copyright years
test, add regression cases for bug #24
minor, introduce dt_separable_p() to denote a predicate ...

that indicates whether or not it's possible to access the
slots .d and .t separately.
minor, separate sexy to daisy/hms sandwich and ymdhms to ymd/hms sandwich
hygiene, use dt_dt_s struct TYP values in dt_separable_p()
Merge branch 'bug/24'

* bug/24:
  hygiene, use dt_dt_s struct TYP values in dt_separable_p()
  minor, separate sexy to daisy/hms sandwich and ymdhms to ymd/hms sandwich
  minor, introduce dt_separable_p() to denote a predicate ...
  test, add regression cases for bug #24
fix, PEBKAC, convert sexy/ymdhms pack according to tgttyp
Merge branch 'bug/ddiff-ymd+sexy'

* bug/ddiff-ymd+sexy:
  fix, PEBKAC, convert sexy/ymdhms pack according to tgttyp
test, adapt regression cases
major, swap DT_MIRACLEDAY and DT_SUNDAY
major, migrate ywd guts to new DT_SUNDAY value
major, migrate ymd guts to new DT_SUNDAY value
major, migrate yd guts to new DT_SUNDAY value
major, migrate daisy guts to new DT_SUNDAY value
hygiene, factor our year getter for ywd->gregorians, __ywd_get_year()
major, migrate ymcw guts to new DT_SUNDAY value
chore, explicitly declaim the day-of-week for week count convention
chore, change signature of __yd_get_wcnt()
major, migrate bizda guts to new DT_SUNDAY value