New unit: Force.ShortTonForce (#821)

* New unit: Force.ShortTonForce

* Adjust abbreviations for Force.ShortTonForce, Force.TonneForce, and Mass.ShortTon

Attempting to standardize the abbreviation format between tonne/ton for mass and force without introducing breaking changes.

Author: lwestfall

Common/UnitDefinitions/Force.json

@@ -53,7 +53,7 @@
       "Localization": [
         {
           "Culture": "en-US",
-          "Abbreviations": [ "Ton" ]
+          "Abbreviations": [ "tf", "Ton" ]
         },
         {
           "Culture": "ru-RU",
@@ -163,6 +163,20 @@
           "Abbreviations": [ "кипф", "койка", "К" ]
         }
       ]
+    },
+    {
+      "SingularName": "ShortTonForce",
+      "PluralName": "ShortTonsForce",
+      "FromUnitToBaseFunc": "x*8.896443230521e3",
+      "FromBaseToUnitFunc": "x/8.896443230521e3",
+      "XmlDocSummary": "The short ton-force is a unit of force equal to 2,000 pounds-force (907.18474 kgf), that is most commonly used in the United States – known there simply as the ton or US ton.",
+      "XmlDocRemarks": "https://en.wikipedia.org/wiki/Ton-force#Short_ton-force",
+      "Localization": [
+        {
+          "Culture": "en-US",
+          "Abbreviations": [ "tf (short)", "t (US)f", "short tons-force" ]
+        }
+      ]
     }
   ]
 }

Common/UnitDefinitions/Mass.json

@@ -59,7 +59,7 @@
       "Localization": [
         {
           "Culture": "en-US",
-          "Abbreviations": [ "short tn", "ST" ]
+          "Abbreviations": [ "t (short)", "short tn", "ST" ]
         },
         {
           "Culture": "ru-RU",

UnitsNet.NumberExtensions.Tests/GeneratedCode/NumberToForceExtensionsTest.g.cs

@@ -32,6 +32,8 @@ public class ForceTests : ForceTestsBase
 
         protected override double OunceForceInOneNewton => 3.596943089595368;
 
+        protected override double ShortTonsForceInOneNewton => 1.12404471549816e-4;
+
         [Fact]
         public void ForceDividedByAreaEqualsPressure()
         {