Also clear screen in Unix and typo.

Terminal.Gui/ConsoleDrivers/NetDriver.cs

@@ -1032,6 +1032,8 @@ namespace Terminal.Gui {
 		{
 			if (Rows > 0) {
 				Console.Clear ();
+				Console.Out.Write ("\x1b[3J");
+				//Console.Out.Write ("\x1b[?25l");
 			}
 		}
 

Terminal.Gui/Core/Application.cs

@@ -100,7 +100,7 @@ namespace Terminal.Gui {
 		}
 
 		/// <summary>
-		/// Used only by <see cref="NetDriver"/> to forcing always setting the cursor position when writing to the screen.
+		/// Used only by <see cref="NetDriver"/> to forcing always moving the cursor position when writing to the screen.
 		/// </summary>
 		public static bool AlwaysSetPosition {
 			get {