Added custom app support.

CustomAppsRunForm.cs

@@ -0,0 +1,58 @@
+using System;
+using System.Collections.Generic;
+using System.ComponentModel;
+using System.Data;
+using System.Drawing;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+using System.Windows.Forms;
+
+namespace MeshCentralRouter
+{
+    public partial class CustomAppsRunForm : Form
+    {
+        private string command = null;
+
+        public CustomAppsRunForm(string command)
+        {
+            this.command = command;
+            InitializeComponent();
+        }
+
+        public string getFinalCommand()
+        {
+            return command.Replace("%L", addressTextBox.Text).Replace("%P", portTextBox.Text);
+        }
+
+        public void UpdateInfo()
+        {
+            commandTextBox.Text = getFinalCommand();
+        }
+
+        private void addressTextBox_TextChanged(object sender, EventArgs e)
+        {
+            UpdateInfo();
+        }
+
+        private void portTextBox_TextChanged(object sender, EventArgs e)
+        {
+            UpdateInfo();
+        }
+
+        private void CustomAppsRunForm_Load(object sender, EventArgs e)
+        {
+            UpdateInfo();
+        }
+
+        private void okButton_Click(object sender, EventArgs e)
+        {
+            DialogResult = DialogResult.OK;
+        }
+
+        private void cancelButton_Click(object sender, EventArgs e)
+        {
+            DialogResult = DialogResult.Cancel;
+        }
+    }
+}