Better init unit from raw

Sources/Units/Units.swift

@@ -108,6 +108,16 @@ public enum Unit: String, CaseIterable, CustomStringConvertible, Codable,
 	case kilocalorie = "kcal"
 	case kilojoule = "kJ"
 
+	public init?(rawValue: String) {
+		if let unit = Unit.allCases.first(where: {
+			$0.rawValue.lowercased() == rawValue
+		}) {
+			self = unit
+			return
+		}
+		return nil
+	}
+
 	public var category: UnitCategory {
 		switch self {
 		case .kilogram, .gram, .milligram, .microgram, .pound, .ounce,