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/LambdaExpressions.cs

@@ -0,0 +1,57 @@
+using System.IO;
+using System.Linq;
+using ClosedXML.Excel;
+using MoreLinq;
+
+namespace ClosedXML_Examples
+{
+    public class LambdaExpressions : IXLExample
+    {
+        public void Create(string filePath)
+        {
+
+            string tempFile = ExampleHelper.GetTempFilePath(filePath);
+            try
+            {
+                new BasicTable().Create(tempFile);
+                var workbook = new XLWorkbook(tempFile);
+                var ws = workbook.Worksheet(1);
+
+                // Define a range with the data
+                var firstDataCell = ws.Cell("B4");
+                var lastDataCell = ws.LastCellUsed();
+                var rngData = ws.Range(firstDataCell.Address, lastDataCell.Address);
+
+                // Delete all rows where Outcast = false (the 3rd column)
+                rngData.Rows() // From all rows
+                        .Where(r => !r.Cell(3).GetBoolean()) // where the 3rd cell of each row is false
+                        .ForEach(r => r.Delete()); // delete the row and shift the cells up (the default for rows in a range)
+
+                //// Put a light gray background to all text cells
+                //rngData.Cells() // From all cells
+                //        .Where(c => c.DataType == XLCellValues.Text) // where the data type is Text
+                //        .ForEach(c => c.Style.Fill.BackgroundColor = XLColor.LightGray); // Fill with a light gray
+
+                var cells = rngData.Cells();
+                var filtered = cells.Where(c => c.DataType == XLDataType.Text);
+                var list = filtered.ToList();
+                foreach (var c in list)
+                {
+                    c.Style.Fill.BackgroundColor = XLColor.LightGray;
+                }
+
+                // Put a thick border to the bottom of the table (we may have deleted the bottom cells with the border)
+                rngData.LastRow().Style.Border.BottomBorder = XLBorderStyleValues.Thick;
+
+                workbook.SaveAs(filePath);
+            }
+            finally
+            {
+                if (File.Exists(tempFile))
+                {
+                    File.Delete(tempFile);
+                }
+            }
+        }
+    }
+}