Change tracerestrict weight ratio properties to use decimals, and the weight unit.

Add {POWER_WEIGHT_RATIO} and {FORCE_WEIGHT_RATIO} string codes.

src/strings_func.h

@@ -139,6 +139,8 @@ uint ConvertDisplaySpeedToKmhishSpeed(uint speed);
 
 void InjectDParam(uint amount);
 
+WChar GetDecimalSeparatorChar();
+
 /**
  * Set a string parameter \a v at index \a n in a given array \a s.
  * @param s Array of string parameters.