Change command X to twoweapon toggle

Explore mode is now an extended command #exploremode.
There's no sense that a command used max. once per game, and
in normal games not at all, takes up a key. So, analogous to
the 'x' command (swap weapons), 'X' now toggles two-weapon
combat.

src/cmd.c

@@ -2411,7 +2411,7 @@ static const struct func_tab cmdlist[] = {
 	{'W', FALSE, dowear},
 	{M('w'), FALSE, dowipe},
 	{'x', FALSE, doswapweapon},
-	{'X', TRUE, enter_explore_mode},
+	{'X', FALSE, dotwoweapon},
 /*	'y', 'Y' : go nw */
 	{'z', FALSE, dozap},
 	{'Z', TRUE, docast},
@@ -2456,6 +2456,7 @@ struct ext_func_tab extcmdlist[] = {
 	{"dip", "dip an object into something", dodip, FALSE},
 	{"enhance", "advance or check weapon and spell skills",
 						enhance_weapon_skill, TRUE},
+	{"exploremode", "enter explore mode", enter_explore_mode, TRUE},
 	{"force", "force a lock", doforce, FALSE},
 	{"invoke", "invoke an object's powers", doinvoke, TRUE},
 	{"jump", "jump to a location", dojump, FALSE},