Add autocomplete for text prompt

Closes #166

src/Spectre.Console/Widgets/Progress/ProgressTaskSettings.cs

@@ -0,0 +1,20 @@
+namespace Spectre.Console
+{
+    /// <summary>
+    /// Represents settings for a progress task.
+    /// </summary>
+    public sealed class ProgressTaskSettings
+    {
+        /// <summary>
+        /// Gets or sets the task's max value.
+        /// Defaults to <c>100</c>.
+        /// </summary>
+        public double MaxValue { get; set; } = 100;
+
+        /// <summary>
+        /// Gets or sets a value indicating whether or not the task
+        /// will be auto started. Defaults to <c>true</c>.
+        /// </summary>
+        public bool AutoStart { get; set; } = true;
+    }
+}