uwp: Add conditionals to unit class generator

Add long/double/decimal constructors and add conditionals
* Convenience constructors for all unit classes
* If UWP, only expose constructor with double type
* Use type alias Culture to represent IFormatProvider vs string

Author: angularsen

UnitsNet/Scripts/Include-GenerateLogarithmicCode.ps1

@@ -24,6 +24,7 @@ function GenerateLogarithmicArithmeticOperators([string]$className, [string]$bas
 
         #region Logarithmic Arithmetic Operators
 
+#if !WINDOWS_UWP
         public static $className operator -($className right)
         {
             return new $className(-right.$baseUnitFieldName);
@@ -66,6 +67,7 @@ function GenerateLogarithmicArithmeticOperators([string]$className, [string]$bas
             // Logarithmic division = subtraction
             return Convert.ToDouble(left.$baseUnitFieldName - right.$baseUnitFieldName);
         }
+#endif
 
         #endregion
 "@;