Add KilogramPerLiter DensityUnit (#627)

* Add KilogramPerLiter DensityUnit

* Update Common/UnitDefinitions/Density.json with BaseUnits

* Update Common/UnitDefinitions/Density.json with BaseUnits

Author: jbrandin

Common/UnitDefinitions/Density.json

@@ -225,6 +225,22 @@
           "Abbreviations": [ "ppg (imp.)" ]
         }
       ]
+    },
+    {
+      "SingularName": "KilogramPerLiter",
+      "PluralName": "KilogramsPerLiter",
+      "BaseUnits": {
+        "L": "Decimeter",
+        "M": "Kilogram"
+      },
+      "FromUnitToBaseFunc": "x*1e3",
+      "FromBaseToUnitFunc": "x/1e3",
+      "Localization": [
+        {
+          "Culture": "en-US",
+          "Abbreviations": [ "kg/l" ]
+        }
+      ]
     }
   ]
-}
+}

UnitsNet.Tests/CustomCode/DensityTests.cs

@@ -30,6 +30,7 @@ public class DensityTests : DensityTestsBase
         protected override double PoundsPerCubicInchInOneKilogramPerCubicMeter => 3.61272923e-5;
 
         protected override double PoundsPerUSGallonInOneKilogramPerCubicMeter => 8.3454045e-3;
+
         protected override double PoundsPerImperialGallonInOneKilogramPerCubicMeter => 1.002241e-2;
 
         protected override double TonnesPerCubicCentimeterInOneKilogramPerCubicMeter => 1e-9;
@@ -84,6 +85,8 @@ public class DensityTests : DensityTestsBase
 
         protected override double MicrogramsPerCubicMeterInOneKilogramPerCubicMeter => 1e9;
 
+        protected override double KilogramsPerLiterInOneKilogramPerCubicMeter => 1e-3;
+
         [Fact]
         public static void DensityTimesVolumeEqualsMass()
         {