fix wrong conversion from meters to yards and from meters to inches (#194)

Co-authored-by: Dzmitry Komar <dzmitrykomar@LT00248-mac.local>

Author: dimonkomaron

lib/src/helpers.dart

@@ -52,14 +52,14 @@ const factors = <Unit, num>{
   Unit.centimeters: earthRadius * 100,
   Unit.degrees: earthRadius / 111325,
   Unit.feet: earthRadius * 3.28084,
-  Unit.inches: earthRadius * 39.370,
+  Unit.inches: earthRadius * 39.3701,
   Unit.kilometers: earthRadius / 1000,
   Unit.meters: earthRadius,
   Unit.miles: earthRadius / 1609.344,
   Unit.millimeters: earthRadius * 1000,
   Unit.nauticalmiles: earthRadius / 1852,
   Unit.radians: 1,
-  Unit.yards: earthRadius / 1.0936,
+  Unit.yards: earthRadius * 1.0936,
 };
 
 const unitsFactors = <Unit, num>{