Initial commit of the ClosedXML library

Establishes the foundational structure, core Excel functionality, and tooling.

- Implements base components for cells, ranges, columns, and rows.
- Integrates a custom calculation engine with a wide range of Excel functions.
- Adds comprehensive support for styling, conditional formatting, data validation, comments, pictures, and charts.
- Configures build setup, project metadata (NuGet), and developer guidelines.
- Includes editor and Git attributes for consistent code style and line endings.

ClosedXML_Examples/PageSetup/Margins.cs

@@ -0,0 +1,36 @@
+using System;
+using ClosedXML.Excel;
+
+
+namespace ClosedXML_Examples.PageSetup
+{
+    public class Margins : IXLExample
+    {
+        #region Methods
+
+        // Public
+        public void Create(String filePath)
+        {
+            var workbook = new XLWorkbook();
+            var ws = workbook.Worksheets.Add("Margins");
+            ws.PageSetup.Margins.Top = 1;
+            ws.PageSetup.Margins.Bottom = 1.25;
+            ws.PageSetup.Margins.Left = 0.5;
+            ws.PageSetup.Margins.Right = 0.75;
+            ws.PageSetup.Margins.Footer = 0.15;
+            ws.PageSetup.Margins.Header = 0.30;
+
+            ws.PageSetup.CenterHorizontally = true;
+            ws.PageSetup.CenterVertically = true;
+
+            workbook.SaveAs(filePath);
+        }
+
+        // Private
+
+        // Override
+
+
+        #endregion
+    }
+}