dlls/kernel subdir (also splitting 16bit APIs in a separate file)
- implemented ntdll.Nt{Lock|Unlock}File, and made use of those for the
  kernel32 equivalent
- implemented a few information classes in NtQueryInformationFile and
  NtSetInformationFile (still lots of missing classes)
- enhanced the get_file_info server request in order to implement
  correctly NtQueryInformationFile (change time & file alloc size)
- rewrote registry loading to comply with latest changes