Closes a previously opened text file.
||The handle of a file, as returned by a previous call to FileOpen.
||Returns 0 if the filehandle is invalid.
Upon termination, AutoIt automatically closes any files it opened, but calling FileClose is still a good idea.
This function is also used to close search handles as returned by FileFindFirstFile().
FileFindFirstFile, FileOpen, FileFindNextFile, FileFlush
Local $handle = FileOpen("test.txt", 0)