'string["substring"]' (like in Ruby) added

Rewrote Dir to make it portable by not using dirent's d_type. Also changed methods a bit to match Ruby's API.

Logger

Fill argument types when passing a function pointer to a C function (like in `->foo` or `->Foo.bar`). Also, renamed `MacroType` to `TypeNode` because now its also used outside macros.

Fix: leaking file descriptors on socket creation errors

Fixed a parser bug where a hash literal of namespaced values couldn't be created ({Foo::A => 1, Foo::B => 2})