feat: parser now writes, added missing fields

updated docs, example, extensive use of Traits with better handling.
valid level 9 phpstan codebase.

src/Traits/HasRegister.php

@@ -0,0 +1,30 @@
+<?php
+
+namespace Ivuorinen\BusinessDataFetcher\Traits;
+
+trait HasRegister
+{
+    /**
+     * @see getRegisterString()
+     * @var int|null $register What register the change is related to.
+     */
+    public int|null $register;
+
+    /**
+     * Get the name of the register.
+     */
+    public function getRegisterString(): string
+    {
+        return match ($this->register) {
+            1 => 'Trade Register',
+            2 => 'Register of Foundations',
+            3 => 'Register of Associations',
+            4 => 'Tax Administration',
+            5 => 'Prepayment Register',
+            6 => 'VAT Register',
+            7 => 'Employer Register',
+            8 => 'Register of bodies liable for tax on insurance premiums',
+            default => 'unknown:' . $this->register,
+        };
+    }
+}