* After discussion with Trent, all INT_PTR references have been removed in favour of the HANDLE it should always have been.  Trent can see no 64bit issues here.

* In this process, I noticed that the close operation was dangerous, in that we could end up passing bogus results to the Win32 API.  These result of the API functions passed the bogus values were never (and still are not) checked, but this is closer to "the right thing" (tm) than before.

Tested on Windows and Linux.