fix github pull request #197 - curses CR handling

Fixes #197
Fixes #195

Add a call to nonl() to tell curses not to convert carriage return (^M)
to newline.  Line input accepts both ^J and ^M as end of line/end of
input, but the core's command processing treats ^M as "unknown command"
(by default; someone could use the BIND option to assign some command
to that character).  The end result is that accidentally pressing the
<return> or <enter> key (or Ctrl+M key combination) won't make the hero
run towards the bottom of the screen as if the user had typed ^J.  The
curses docs also claim that it allows more optimization during screen
updating by making ^J work as plain linefeed rather than ^M^J newline.

The tty interface can achieve this (the 'do not convert ^M to ^J part',
not the 'more optimization' part) by issuing the command 'stty -icrnl'
(on Unix or sufficiently Unix-like system) prior to running nethack,
but that has no effect when using the curses interface (at least with
ncurses on OSX where I've tested it).

A better fix would be to look up the current terminal settings at
program startup and only call nonl() if -crnl was in effect so that
curses and tty would behave the same in this regard, but curses is
supposed to let us avoid those sorts of messy details....

win/curses/cursmain.c

@@ -143,6 +143,8 @@ curses_init_nhwindows(int *argcp UNUSED,
 #endif
     noecho();
     raw();
+    nonl(); /* don't force ^M into newline (^J); input accepts them both
+             * but as a command, accidental <enter> won't run South */
     meta(stdscr, TRUE);
     orig_cursor = curs_set(0);
     keypad(stdscr, TRUE);