IOS-80: shared measurement formatter.

1Weather/Extensions/Measurement+String.swift

@@ -7,9 +7,13 @@
 
 import Foundation
 
+extension MeasurementFormatter {
+    fileprivate static let oneWeatherSharedFormatter = MeasurementFormatter()
+}
+
 extension Measurement {
     private static func formatter(style: Formatter.UnitStyle, unitOptions: MeasurementFormatter.UnitOptions = .providedUnit) -> MeasurementFormatter {
-        let fmt = MeasurementFormatter()
+        let fmt = MeasurementFormatter.oneWeatherSharedFormatter
         fmt.locale = Settings.shared.locale
         fmt.unitStyle = style
         fmt.unitOptions = unitOptions