Don't bind quit to any key by default

Quit is not a commmand you usually need very often, and generally
don't want to use by accident.

Apparently, on Spanish keyboard layout, n-with-tilde is interpreted
by the Windows NetHack as M-q, and the key is next to l. Loot also
asks for confirmation, just like quit.

Prevent stuff like this by not binding the quit command to any key.

doc/Guidebook.tex

@@ -953,11 +953,7 @@ Quaff (drink) something (potion, water, etc).
 \item[\tb{Q}]
 Select an object for your quiver, quiver sack, or just generally at
 the ready (only one of these is available at a time).  You can then throw
-this (or one of these) using
-the `f' command.\\
-%.lp ""
-(In versions prior to 3.3 this was the command to quit
-the game, which has been moved to ``{\tt \#quit}''.)
+this (or one of these) using the `f' command.
 %.lp
 \item[\tb{r}]
 Read a scroll or spellbook.
@@ -1500,8 +1496,7 @@ Put on an accessory (ring, amulet, etc). Default key is `{\tt P}'.
 Quaff (drink) something. Default key is `{\tt q}'.
 %.lp
 \item[\tb{\#quit}]
-Quit the program without saving your game. Autocompletes.
-Default key is `{\tt M-q}'.\\
+Quit the program without saving your game. Autocompletes.\\
 %.lp ""
 Since using this command by accident would throw away the current game,
 you are asked to confirm your intent before quitting.
@@ -1893,9 +1888,6 @@ another command, so the three key combination meta+shift+letter is needed.
 \item[\tb{M-p}]
 {\tt\#pray}
 %.Ip
-\item[\tb{M-q}]
-{\tt\#quit}
-%.lp
 \item[\tb{M-r}]
 {\tt\#rub}
 %.lp