Add support for manipulating individual table rows

Closes #500

examples/Console/Live/Live.csproj

@@ -5,7 +5,7 @@
     <TargetFramework>net5.0</TargetFramework>
     <ExampleTitle>Live</ExampleTitle>
     <ExampleDescription>Demonstrates how to do live updates.</ExampleDescription>
-    <ExampleGroup>Misc</ExampleGroup>
+    <ExampleGroup>Live</ExampleGroup>
   </PropertyGroup>
 
   <ItemGroup>

examples/Console/LiveTable/LiveTable.csproj

@@ -0,0 +1,15 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <OutputType>Exe</OutputType>
+    <TargetFramework>net5.0</TargetFramework>
+    <ExampleTitle>LiveTable</ExampleTitle>
+    <ExampleDescription>Demonstrates how to do live updates in a table.</ExampleDescription>
+    <ExampleGroup>Live</ExampleGroup>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <ProjectReference Include="..\..\Shared\Shared.csproj" />
+  </ItemGroup>
+
+</Project>

examples/Console/LiveTable/Program.cs

@@ -0,0 +1,86 @@
+using System;
+using System.Linq;
+using System.Threading.Tasks;
+
+namespace Spectre.Console.Examples
+{
+    public static class Program
+    {
+        private const int NumberOfRows = 10;
+
+        private static readonly Random _random = new();
+        private static readonly string[] _exchanges = new string[]
+        {
+            "SGD", "SEK", "PLN",
+            "MYR", "EUR", "USD",
+            "AUD", "JPY", "CNH",
+            "HKD", "CAD", "INR",
+            "DKK", "GBP", "RUB",
+            "NZD", "MXN", "IDR",
+            "TWD", "THB", "VND",
+        };
+
+        public static async Task Main(string[] args)
+        {
+            var table = new Table().Expand().BorderColor(Color.Grey);
+            table.AddColumn("[yellow]Source currency[/]");
+            table.AddColumn("[yellow]Destination currency[/]");
+            table.AddColumn("[yellow]Exchange rate[/]");
+
+            AnsiConsole.MarkupLine("Press [yellow]CTRL+C[/] to exit");
+
+            await AnsiConsole.Live(table)
+                .AutoClear(false)
+                .Overflow(VerticalOverflow.Ellipsis)
+                .Cropping(VerticalOverflowCropping.Bottom)
+                .StartAsync(async ctx =>
+                {
+                    // Add some initial rows
+                    foreach (var _ in Enumerable.Range(0, NumberOfRows))
+                    {
+                        AddExchangeRateRow(table);
+                    }
+
+                    // Continously update the table
+                    while (true)
+                    {
+                        // More rows than we want?
+                        if (table.Rows.Count > NumberOfRows)
+                        {
+                            // Remove the first one
+                            table.Rows.RemoveAt(0);
+                        }
+
+                        // Add a new row
+                        AddExchangeRateRow(table);
+
+                        // Refresh and wait for a while
+                        ctx.Refresh();
+                        await Task.Delay(400);
+                    }
+                });
+        }
+
+        private static void AddExchangeRateRow(Table table)
+        {
+            var (source, destination, rate) = GetExchangeRate();
+            table.AddRow(
+                source, destination,
+                _random.NextDouble() > 0.35D ? $"[green]{rate}[/]" : $"[red]{rate}[/]");
+        }
+
+        private static (string Source, string Destination, double Rate) GetExchangeRate()
+        {
+            var source = _exchanges[_random.Next(0, _exchanges.Length)];
+            var dest = _exchanges[_random.Next(0, _exchanges.Length)];
+            var rate = 200 / ((_random.NextDouble() * 320) + 1);
+
+            while (source == dest)
+            {
+                dest = _exchanges[_random.Next(0, _exchanges.Length)];
+            }
+
+            return (source, dest, rate);
+        }
+    }
+}