WIP: named arguments

[i582]

RFC: https://wiki.php.net/rfc/named_params

TODO

• Rename arguments in functions.txt to match PHP names
• Variadic functions and argument unpacking
• func_get_args() and friends
• call_user_func() and friends
• __call()
• Think about checks if the names of the arguments in the functions of the parent class and child class are different

interface I {
    public function test($foo, $bar);
}
 
class C implements I {
    public function test($a, $b) {}
}

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