Refactorings

- important curl and wget improvements
- initial test coverage
- setters and getters in Request classes
- namespace fixes
- some additions in README
- docblocks and code-style

src/HttpVersions.php

@@ -0,0 +1,21 @@
+<?php
+
+declare(strict_types=1);
+
+namespace PmConverter;
+
+enum HttpVersions: string
+{
+    case Version10 = '1.0';
+    case Version11 = '1.1';
+    case Version2 = '2';
+    case Version3 = '3';
+
+    public static function values(): array
+    {
+        return array_combine(
+            array_column(self::cases(), 'name'),
+            array_column(self::cases(), 'value'),
+        );
+    }
+}