Add link support for supported terminals

Also refactors the code quite a bit, to make it a bit more
easier to add features like this in the future.

Closes #75

examples/Links/Program.cs

@@ -0,0 +1,22 @@
+using System;
+using Spectre.Console;
+
+namespace Links
+{
+    public static class Program
+    {
+        public static void Main()
+        {
+            if (AnsiConsole.Capabilities.SupportLinks)
+            {
+                AnsiConsole.MarkupLine("[link=https://patriksvensson.se]Click to visit my blog[/]!");
+            }
+            else
+            {
+                AnsiConsole.MarkupLine("[red]It looks like your terminal doesn't support links[/]");
+                AnsiConsole.WriteLine();
+                AnsiConsole.MarkupLine("[yellow](╯°□°)╯[/]︵ [blue]┻━┻[/]");
+            }
+        }
+    }
+}