Support objects as container variables for factory functions

[clue]

This changeset adds support for object variables in the container configuration for all factory functions:

<?php

require __DIR__ . '/../vendor/autoload.php';

$container = new FrameworkX\Container([
    Acme\Todo\UserController::class => function (stdClass $site) {
        // example UserController class uses $site from explicit container configuration
        return new Acme\Todo\UserController($site);
    },
    'site' => (object) ['name' => 'ACME']
]);

// …

The previous version only supported scalar values (string, int, float, bool), we now support all object and scalar values. This is the next step in adding better configuration support and support for environment variables and .env (dotenv) files as discussed in #101.

Builds on top of #179, #178, #163, #97, #95 and others