Added better header parsing to Request-class.

- Added `tryParse` argument to the `getHeader` method. When enabled the method will try to parse headers from both server and client-side (enabled by default).
- Simplified references that checks for both variants of header (http/non http).
- Simplified getIp method of the Request-class.

src/Pecee/Http/Middleware/BaseCsrfVerifier.php

@@ -67,7 +67,7 @@ class BaseCsrfVerifier implements IMiddleware
 
             $token = $request->getInputHandler()->value(
                 static::POST_KEY,
-                $request->getHeader(static::HEADER_KEY) ?? $request->getHeader('HTTP-' . static::HEADER_KEY),
+                $request->getHeader(static::HEADER_KEY),
                 Request::$requestTypesPost
             );