Add ff_abs() function for float absolute value

ttcn/Common/LibItsCommon_Functions.ttcn

@@ -55,6 +55,20 @@ module LibItsCommon_Functions {
             return p_number;    
         }
 
+        /**
+         * @desc    Computes the absolute value of an integer 
+         * @param   p_number    the number
+         * @return  Absolute value of the number
+         */
+        function ff_abs(in float p_number) 
+        return float {
+            
+            if(p_number < 0.0) {
+                return 0.0 - p_number;
+            }
+            return p_number;    
+        }
+
         /**
          * @desc    Compares two values and returns the lowest onde  
          * @param   p_a     First value