Update to 20160106 OS X Preview for Developers release.

byuu says:

New update. Most of the work today went into eliminating hiro::Image
from all objects in all ports, replacing with nall::image. That took an
eternity.

Changelog:
- fixed crashing bug when loading games [thanks endrift!!]
- toggling "show status bar" option adjusts window geometry (not
  supposed to recenter the window, though)
- button sizes improved; icon-only button icons no longer being cut off

nall/encode/base64.hpp

@@ -1,5 +1,4 @@
-#ifndef NALL_ENCODE_BASE64_HPP
-#define NALL_ENCODE_BASE64_HPP
+#pragma once
 
 namespace nall { namespace Encode {
 
@@ -66,5 +65,3 @@ inline auto Base64(const string& text, const string& format = "MIME") -> string
 }
 
 }}
-
-#endif