Implemented additional methods to the csharp wrapper

highs/interfaces/highs_csharp_api.cs

@@ -466,6 +466,15 @@ private static extern int Highs_addCols(
     [DllImport(highslibname)]
     private static extern int Highs_getInt64InfoValue(IntPtr highs, string info, out long value);
 
+    [DllImport(highslibname)]
+    private static extern int Highs_changeObjectiveOffset(IntPtr highs, double offset);
+
+    [DllImport(highslibname)]
+    private static extern int Highs_addLinearObjective(IntPtr highs, double weight, double offset, double[] coefficients, double abs_tolerance, double rel_tolerance, int priority);
+
+    [DllImport(highslibname)]
+    private static extern int Highs_clearLinearObjectives(IntPtr highs);
+
     [DllImport(highslibname)]
     private static extern int Highs_setSolution(IntPtr highs, double[] col_value, double[] row_value, double[] col_dual, double[] row_dual);
 
@@ -1023,6 +1032,21 @@ public SolutionInfo getInfo()
         return info;
     }
 
+    public HighsStatus changeObjectiveOffset(double offset)
+    {
+        return (HighsStatus)HighsLpSolver.Highs_changeObjectiveOffset(this.highs, offset);
+    }
+
+    public HighsStatus addLinearObjective(double weight, double offset, double[] coefficients, double abs_tolerance, double rel_tolerance, int priority)
+    {
+        return (HighsStatus)HighsLpSolver.Highs_addLinearObjective(this.highs, weight, offset, coefficients, abs_tolerance, rel_tolerance, priority);
+    }
+
+    public HighsStatus clearLinearObjectives()
+    {
+        return (HighsStatus)HighsLpSolver.Highs_clearLinearObjectives(this.highs);
+    }
+
     public HighsStatus setSolution(HighsSolution solution)
     {
         return (HighsStatus)HighsLpSolver.Highs_setSolution(this.highs, solution.colvalue, solution.rowvalue, solution.coldual, solution.rowdual);