Work around mono crashing on Rows.Clear()

Mono will crash if you do a Rows.Clear() and the first row isnt visible.  To
work around this, when running under mono force scroll to [0,0] cell before
issuing the Clear().

https://bugzilla.xamarin.com/show_bug.cgi?id=24372

Renamed Settings.MonoFileIO to Settings.IsUnix
Created Settings.IsMono

ROMVault2/FrmSetDir.cs

@@ -35,6 +35,9 @@ namespace ROMVault2
 
         private void UpdateGrid()
         {
+            if (Settings.IsMono && DataGridGames.RowCount > 0)
+                DataGridGames.CurrentCell = DataGridGames[0,0];
+
             DataGridGames.Rows.Clear();
             foreach (DirMap t in Settings.DirPathMap)
             {