DisplayConfig defaults button should whack the padding back to 0

Author: zeromus

src/BizHawk.Client.EmuHawk/config/DisplayConfig.cs

@@ -371,6 +371,10 @@ private void BtnDefaults_Click(object sender, EventArgs e)
 			rbFinalFilterBilinear.Checked = true;
 			checkLetterbox.Checked = true;
 			rbUseSystem.Checked = true;
+			txtCropLeft.Text = "0";
+			txtCropTop.Text = "0";
+			txtCropRight.Text = "0";
+			txtCropBottom.Text = "0";
 		}
 	}
 }