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/Misc/WorkbookProperties.cs

@@ -0,0 +1,75 @@
+using System;
+using ClosedXML.Excel;
+
+
+namespace ClosedXML_Examples.Misc
+{
+    public class WorkbookProperties : IXLExample
+    {
+        #region Variables
+
+        // Public
+
+        // Private
+
+
+        #endregion
+
+        #region Properties
+
+        // Public
+
+        // Private
+
+        // Override
+
+
+        #endregion
+
+        #region Events
+
+        // Public
+
+        // Private
+
+        // Override
+
+
+        #endregion
+
+        #region Methods
+
+        // Public
+        public void Create(String filePath)
+        {
+            var wb = new XLWorkbook();
+            var ws = wb.Worksheets.Add("Workbook Properties");
+
+            wb.Properties.Author = "theAuthor";
+            wb.Properties.Title = "theTitle";
+            wb.Properties.Subject = "theSubject";
+            wb.Properties.Category = "theCategory";
+            wb.Properties.Keywords = "theKeywords";
+            wb.Properties.Comments = "theComments";
+            wb.Properties.Status = "theStatus";
+            wb.Properties.LastModifiedBy = "theLastModifiedBy";
+            wb.Properties.Company = "theCompany";
+            wb.Properties.Manager = "theManager";
+
+            // Creating/Using custom properties
+            wb.CustomProperties.Add("theText", "XXX");
+            wb.CustomProperties.Add("theDate", new DateTime(2011, 1, 1, 17, 0, 0, DateTimeKind.Utc)); // Use UTC to make sure test can be run in any time zone
+            wb.CustomProperties.Add("theNumber", 123.456);
+            wb.CustomProperties.Add("theBoolean", true);
+
+            wb.SaveAs(filePath);
+        }
+
+        // Private
+
+        // Override
+
+
+        #endregion
+    }
+}