Added file tranfer overwrite warning.

FileConfirmOverwriteForm.cs

@@ -0,0 +1,25 @@
+using System;
+using System.Windows.Forms;
+
+namespace MeshCentralRouter
+{
+    public partial class FileConfirmOverwriteForm : Form
+    {
+        public FileConfirmOverwriteForm()
+        {
+            InitializeComponent();
+        }
+
+        public string mainTextLabel { get { return mainLabel.Text; } set { mainLabel.Text = value; } }
+
+        private void okButton_Click(object sender, EventArgs e)
+        {
+            DialogResult = DialogResult.OK;
+        }
+
+        private void cancelButton_Click(object sender, EventArgs e)
+        {
+            DialogResult = DialogResult.Cancel;
+        }
+    }
+}