fix rest_on_space

When rest_on_space is On, assign same function as for #wait to the
<space> key.  When Off, set that key to Null instead.  Binding some
other command to <space> when rest_on_space is Off doesn't work but
I would classify that as something to be discouraged anyway.

doc/fixes37.0

@@ -980,8 +980,8 @@ changing engraving to an occupation resulted in not dulling a weapon used to
 a change to wounded legs handling resulted in not recovering lost dexterity
 	or receiving the "leg(s) feel better" message if wound time expired
 	rather than having legs be explicitly healed
-turning movement into commands interfered with using pick-axe plus autodig
-	in downward direction
+turning movement into commands broke the rest_on_space option; it also
+	interfered with using pick-axe plus autodig in downward direction
 
 curses: 'msg_window' option wasn't functional for curses unless the binary
 	also included tty support

include/extern.h

@@ -252,6 +252,7 @@ extern const char *key2extcmddesc(uchar);
 extern boolean bind_specialkey(uchar, const char *);
 extern void parseautocomplete(char *, boolean);
 extern void reset_commands(boolean);
+extern void update_rest_on_space(void);
 extern void rhack(char *);
 extern int doextlist(void);
 extern int extcmd_via_menu(void);

src/cmd.c

@@ -2574,9 +2574,10 @@ commands_init(void)
     (void) bind_key(M('2'), "twoweapon");
     (void) bind_key(M('n'), "name");
     (void) bind_key(M('N'), "name");
-
-    /* wait_on_space */
+#if 0
+    /* don't do this until the rest_on_space option is set or cleared */
     (void) bind_key(' ',    "wait");
+#endif
 }
 
 static boolean
@@ -3573,6 +3574,22 @@ reset_commands(boolean initial)
             (void) bind_key_fn(M(g.Cmd.dirchars[i]), move_funcs[i][MV_RUSH]);
         }
     }
+    update_rest_on_space();
+}
+
+void
+update_rest_on_space(void)
+{
+    /* cloned from extcmdlist['.'], then slightly modified to be distinct;
+       donull is all that's needed for it to operate; command name and
+       description get shown by help menu's "Info on what a given key does"
+       (which runs the '&' command) and "Full list of keyboard commands" */
+    static const struct ext_func_tab restonspace = {
+        ' ', "wait", "rest one move via 'rest_on_space' option",
+        donull, (IFBURIED | CMD_M_PREFIX), "waiting"
+    };
+
+    g.Cmd.commands[' '] = flags.rest_on_space ? &restonspace : 0;
 }
 
 /* commands which accept 'm' prefix to request menu operation */

src/options.c

@@ -4225,6 +4225,9 @@ optfn_boolean(int optidx, int req, boolean negated, char *opts, char *op)
         case opt_mention_decor:
             iflags.prev_decor = STONE;
             break;
+        case opt_rest_on_space:
+            update_rest_on_space();
+            break;
         }
 
         /* boolean value has been toggled but some option changes can
@@ -5908,6 +5911,7 @@ initoptions_finish(void)
         }
     }
 #endif
+    update_rest_on_space();
     g.opt_initial = FALSE;
     return;
 }