date.toRelative() returns empty string for languages which have not a full set of plural rules

[anton-kaliuzhnyi-altexsoft]

If some language has not a full set of plural rules SwiftDate returns an empty string ("") from date.toRelative().

For example, for Russian "2 hours ago" is not returned at all, because it falls to a "few" rule which is absent in the dictionary:

public class lang_ru: RelativeFormatterLang {
	// ...
	private var _long: [String: Any] {
		return [
		"hour": [
		"current": "в этот час",
		"past": [
			"one": "{0} час назад",
			"many": "{0} часов назад",
			"other": "{0} часа назад"
		],
	// ...

[0xMarK]

@malcommac The fix is available in Pull Request #631 Please review and accept it if it is ok.

[malcommac]

Accepted, on track for 5.1.0. Thanks