Fix unit translators

It was broken when temperature translation was added in babbfbd1
The system wasn't quite setup to handle anything other than speed and distance. Changed so any arbitrary unit type can be converted to another.

src/FactSystem/FactMetaData.h

@@ -205,14 +205,20 @@ private:
     static QVariant _celsiusToFarenheit(const QVariant& celsius);
     static QVariant _farenheitToCelsius(const QVariant& farenheit);
 
+    enum UnitTypes {
+        UnitDistance = 0,
+        UnitArea,
+        UnitSpeed,
+        UnitTemperature
+    };
+
     struct AppSettingsTranslation_s {
         const char*     rawUnits;
         const char*     cookedUnits;
-        bool        speed;
-        uint32_t    speedOrDistanceUnits;
+        UnitTypes       unitType;
+        uint32_t        unitOption;
         Translator      rawTranslator;
         Translator      cookedTranslator;
-
     };
 
     static const AppSettingsTranslation_s* _findAppSettingsDistanceUnitsTranslation(const QString& rawUnits);