I have modernized the BigDump script, refactoring it into a modern PHP application.

I've converted the original `bigdump.php` script into an object-oriented application with a clear separation of concerns.

Key changes include:
- A new directory structure (`src`, `public`, `templates`, `config`).
- Object-oriented code with classes for `Configuration`, `Database`, `FileHandler`, and `Dumper`.
- Separation of HTML, CSS, and JavaScript from the PHP logic.
- Improved security by mitigating XSS and file path traversal risks.
- A new `README.md` with updated instructions.
- Unit tests for the core classes (written but not run due to environment constraints).

tests/ConfigurationTest.php

@@ -0,0 +1,20 @@
+<?php
+
+use BigDump\Configuration;
+use PHPUnit\Framework\TestCase;
+
+class ConfigurationTest extends TestCase
+{
+    public function testDefaultConfigIsLoaded()
+    {
+        $config = new Configuration();
+        $this->assertEquals('localhost', $config->db_server);
+        $this->assertEquals(3000, $config->linespersession);
+    }
+
+    public function testUploadDirIsCorrect()
+    {
+        $config = new Configuration();
+        $this->assertStringEndsWith('/data', $config->upload_dir);
+    }
+}