the lexicon owns the weekdays and the oblique small numbers (V-581)

Weekday names lived in four files outside internal/lexicon and each copy was
short in a different direction. The habit map had the prepositional plural of
Sunday and no dative of Wednesday. The plan refusal had the accusative of
Wednesday and not the prepositional. cmd/mavend matched the stem.

Weekdays hands out the seven nominatives whole, because every Russian case
lemmatises to one of them and the case is morph's question. WeekdayEnglish is
the half that has to be data: the vendored dictionary is Russian and leaves
mondays as it found it.

Cardinals gain the dative and instrumental of one to four. A spoken hour
declines and five upward has one oblique form for the genitive, dative and
prepositional, so pyati was already whole while dvum was missing and k dvum
chasam is an hour he says.

internal/lexicon/lexicon.go

@@ -62,7 +62,7 @@ func mustLoad() lexiconFile {
 	}
 	for _, name := range []string{
 		"interrogatives", "capture_verbs", "narrative_requests", "cardinals", "ordinals",
-		"day_offsets", "weekdays", "months_genitive", "hours_spoken",
+		"day_offsets", "weekdays", "weekdays_english", "months_genitive", "hours_spoken",
 		"not_place_after_v", "parts_of_day", "reminder_verbs", "half_hour",
 		"filler_particles", "task_done_words", "task_drop_words",
 		"confirm_yes", "confirm_no",
@@ -283,6 +283,20 @@ func DayOffsetIn(text string) (int, bool) {
 // Go's time.Weekday. An index off the end returns "".
 func Weekday(i int) string { return at("weekdays", i) }
 
+// Weekdays returns the seven Russian names in one slice, Sunday first, for a
+// caller matching a token against all of them rather than rendering one. Only
+// the nominative is here: every other case lemmatises to it, so an oblique form
+// is morph's question and not a second list (V-581).
+func Weekdays() []string { return words("weekdays") }
+
+// WeekdayEnglish reports the Go time.Weekday index an English weekday names,
+// singular or plural. English needs the list that Russian does not, because the
+// vendored dictionary is Russian and leaves "mondays" as it found it.
+func WeekdayEnglish(word string) (int, bool) {
+	n, ok := ru.Sets["weekdays_english"].Values[norm(word)]
+	return n, ok
+}
+
 // MonthGenitive returns the month name a date takes — "10 июля", not "июль".
 // The set is 1-indexed, so MonthGenitive(int(t.Month())) is the whole call.
 func MonthGenitive(m int) string { return at("months_genitive", m) }