- better support for non-blocking COMM and socket read/writes:

- better support for non-blocking COMM and socket read/writes:
  + added necessary semantics to fd flags
  + no longer uses fd type (but fd flags) read/write semantic behavior
- fixed socket code to use the proper manifest constants
- fixes for kernel32.GetOverlappedResult without hEvent set
- in ntdll.Nt{Read|Write}File
  + always reset the event
  + added support for longlong offsets
  + better object disposal in error handling code paths