change references from winnt to windows

rename sys/winnt to sys/windows
move vs (visual studio) folder out of win/win32 and into sys/windows
rename include/ntconf.h to include/windconf.h
rename winnt.c to windsys.c
place visual studio projects into individual subfolders.

This will hopefully resolve GitHub issue #484 as well.

sys/windows/console.rc

@@ -0,0 +1,49 @@
+/* NetHack 3.7	console.rc	$NHDT-Date: 1596498311 2020/08/03 23:45:11 $  $NHDT-Branch: NetHack-3.7 $:$NHDT-Revision: 1.14 $ */
+/* Copyright (c) Yitzhak Sapir, 2002. 					*/
+/* NetHack may be freely redistributed.  See license for details. 	*/
+
+#include "windows.h"
+
+1 ICON DISCARDABLE "NetHack.ICO"
+
+/////////////////////////////////////////////////////////////////////////////
+//
+// Version
+//
+
+VS_VERSION_INFO VERSIONINFO
+ FILEVERSION 3,7,0,0
+ PRODUCTVERSION 3,7,0,0
+ FILEFLAGSMASK 0x1fL
+#ifdef _DEBUG
+ FILEFLAGS 0x9L
+#else
+ FILEFLAGS 0x8L
+#endif
+ FILEOS 0x4L
+ FILETYPE 0x0L
+ FILESUBTYPE 0x0L
+BEGIN
+    BLOCK "StringFileInfo"
+    BEGIN
+        BLOCK "040904b0"
+        BEGIN
+            VALUE "FileDescription", "NetHack for Windows - TTY Interface\0"
+            VALUE "FileVersion", "3.7.0\0"
+            VALUE "InternalName", "NetHack\0"
+            VALUE "LegalCopyright", "Copyright (C) 1985 - 2020.  By Stichting Mathematisch Centrum and M. Stephenson.  See license for details.\0"
+            VALUE "OriginalFilename", "NetHack.exe\0"
+            VALUE "PrivateBuild", "050102\0"
+            VALUE "ProductName", "NetHack\0"
+            VALUE "ProductVersion", "3.7.0\0"
+        END
+    END
+    BLOCK "VarFileInfo"
+    BEGIN
+        VALUE "Translation", 0x409, 1200
+    END
+END
+
+
+/*console.rc*/
+