move out-of-date hints files to the outdated folder.
rename the hints files, and hints/include files that are currently
named *.2020 to *.370 (next release number).
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.
On some platforms this may require:
make spotless
make fetch-lua
I did attempt to force a reminder message about the latter to
Makefile.top this time, and hope that works correctly for everyone.
