* nt/Makefile.NT, nt/Makefile.VC4: rewritten for GNU make.
Use gmake -f Makefile.VC4 to compile.
* nt/*.c: config.h is included before all other code.
* nt/config.h: added some definitions, because some
compilers don't accept long command lines.
* nt/Makefile.VC1: removed :-( It didn't work anyways.
* nt/slint.nt.c: can be compiled under OS/2 too
* nt/key.nt.c: correct_key_code was called twice. Shifted
functional keys supported. Alt-F1 and Alt-F2 work as F11 and F12.
Alt-F7 works as Shift-Alt-? (used for find file). Function
alt_pressed() and ctrl_pressed() introduced.