more wizard/explore mode control (trunk only)

Wizard mode or explore mode can be forced on (via -D or -X on the
command line, or now via OPTIONS=playmode:debug|explore) when restoring
a saved game; explore mode handling was confined to restgamestate(), but
wizard mode handling was replicated in every main().  Treat `wizard' the
same as `discover'.  Also, prevent a new game started when restore fails
from using the old game's option settings if partial restore attempt got
far enough to load the flags struct.  And update bemain.c and macmain.c
to catch up with the others modified by the playmode patch.

sys/unix/unixmain.c

@@ -234,12 +234,6 @@ char *argv[];
 	display_gamewindows();
 
 	if ((fd = restore_saved_game()) >= 0) {
-#ifdef WIZARD
-		/* Since wizard is actually flags.debug, restoring might
-		 * overwrite it.
-		 */
-		boolean remember_wiz_mode = wizard;
-#endif
 		const char *fq_save = fqname(SAVEF, SAVEPREFIX, 1);
 
 		(void) chmod(fq_save,0);	/* disallow parallel restores */
@@ -254,9 +248,6 @@ char *argv[];
 		mark_synch();	/* flush output */
 		if (dorecover(fd)) {
 		    resuming = TRUE;	/* not starting new game */
-#ifdef WIZARD
-		    if (!wizard && remember_wiz_mode) wizard = TRUE;
-#endif
 		    wd_message();
 		    if (discover || wizard) {
 			if(yn("Do you want to keep the save file?") == 'n')