[TASK] Fix PHP 8.4 compatibility

Defaulting to null without being nullable (?Foo) is deprecated for typed
parameters in PHP 8.4, therefore nullable is now specified explicitly.
This change requires at least PHP 7.1 (which has been made a minimum
with the parent commit).

Additional the call to str_getcsv is adapted to set all optional
arguments as the defaults will change in PHP >= 9 and PHP 8.4
deprecated the omission of the optional arguments.

Fixes #31

Author: bnf

src/ClassAliasMapGenerator.php

@@ -46,7 +46,7 @@ class ClassAliasMapGenerator
      * @param Composer $composer
      * @param IOInterface $io
      */
-    public function __construct(Composer $composer, IOInterface $io = null, $config = null)
+    public function __construct(Composer $composer, ?IOInterface $io = null, $config = null)
     {
         $this->composer = $composer;
         $this->io = $io ?: new NullIO();

src/Config.php

@@ -39,7 +39,7 @@ class Config
      * @param PackageInterface $package
      * @param IOInterface $io
      */
-    public function __construct(PackageInterface $package, IOInterface $io = null)
+    public function __construct(PackageInterface $package, ?IOInterface $io = null)
     {
         $this->io = $io ?: new NullIO();
         $this->setAliasLoaderConfigFromPackage($package);
@@ -55,7 +55,8 @@ public function get($configKey)
             throw new \InvalidArgumentException('Configuration key must not be empty', 1444039407);
         }
         // Extract parts of the path
-        $configKey = str_getcsv($configKey, '.');
+        $configKey = str_getcsv($configKey, '.',  '"', '\\');
+
         // Loop through each part and extract its value
         $value = $this->config;
         foreach ($configKey as $segment) {

src/IncludeFile.php

@@ -48,7 +48,7 @@ class IncludeFile
      * @param TokenInterface[] $tokens
      * @param Filesystem $filesystem
      */
-    public function __construct(IOInterface $io, Composer $composer, array $tokens, Filesystem $filesystem = null)
+    public function __construct(IOInterface $io, Composer $composer, array $tokens, ?Filesystem $filesystem = null)
     {
         $this->io = $io;
         $this->composer = $composer;