Remove `get`, `has`, `let` and `set` Method(s) from Non-Static Class(es)

[Taufik Nurrohman]

Use the built-in __get, __isset, __set and __unset method overloading instead.

Before

if (!$page->has('foo')) {
    $page->set('foo', ['bar' => 1]);
}

echo $page->get('foo.bar');
echo $page->get('foo-bar');

After

if (!isset($page->foo)) {
    $page->foo = ['bar' => 1];
}

echo $page->foo->bar ?? null;
echo $page->fooBar;