TCursorDown()
TCursorDown(void)
TCursorDown(){	register TScreen *screen = &term->screen;	register struct Tek_Char *t;	register int l;	t = &TekChar[screen->cur.fontsize];	if((l = screen->cur_Y / t->vsize - 1) < 0) {		l = t->nlines - 1;		if((screen->margin = !screen->margin) != MARGIN1) {			if(screen->cur_X < TEKWIDTH / 2)				screen->cur_X += TEKWIDTH / 2;		} else if(screen->cur_X >= TEKWIDTH / 2)			screen->cur_X -= TEKWIDTH / 2;	}	screen->cur_Y = l * t->vsize;}