add 'montelecontrol' option (wizard-mode only)

Add a new debugging option, 'montelecontrol', that allows a wizard-
mode player to choose a teleporting monster's destination.  If player
picks a bad spot, confirmation will be requested.  If accepted, the
spot will be used even though the consequences could be bad; that's
on the player.  If rejected, the destination will be assigned as if
no control had been attempted rather than try again.

The fuzzer isn't allowed to override a bad spot if it tries to pick
one.  That would probably trigger a sanity_check warning; the fuzzer
causes impossible warnings to behave as if panic, so accepting a bad
spot would just be fuzzer suicide.  It is allowed to randomly set the
option and maybe--though extremely unlikely--randomly pick a valid
controlled destination.

include/extern.h

@@ -2820,6 +2820,7 @@ extern void level_tele_trap(struct trap *, unsigned);
 extern void rloc_to(struct monst *, coordxy, coordxy);
 extern void rloc_to_flag(struct monst *, coordxy, coordxy, unsigned);
 extern boolean rloc(struct monst *, unsigned);
+extern boolean control_mon_tele(struct monst *, coord *cc, unsigned, boolean);
 extern boolean tele_restrict(struct monst *);
 extern void mtele_trap(struct monst *, struct trap *, int);
 extern int mlevel_tele_trap(struct monst *, struct trap *, boolean, int);

include/flag.h

@@ -236,6 +236,7 @@ struct instance_flags {
     boolean debug_mongen;  /* debug: prevent monster generation */
     boolean debug_hunger;  /* debug: prevent hunger */
     boolean mon_polycontrol; /* debug: control monster polymorphs */
+    boolean mon_telecontrol; /* debug: control monster teleports */
     boolean in_dumplog;    /* doing the dumplog right now? */
     boolean in_parse;      /* is a command being parsed? */
      /* suppress terminate during options parsing, for --showpaths */

include/optlist.h

@@ -454,6 +454,9 @@ static int optfn_##a(int, int, boolean, char *, char *);
     NHOPTB(monpolycontrol, Advanced, 0, opt_in, set_wizonly,
            Off, Yes, No, No, NoAlias, &iflags.mon_polycontrol, Term_False,
            "control monster polymorphs")
+    NHOPTB(montelecontrol, Advanced, 0, opt_in, set_wizonly,
+           Off, Yes, No, No, NoAlias, &iflags.mon_telecontrol, Term_False,
+           "control monster teleport destinations")
     NHOPTC(monsters, Advanced, MAXMCLASSES, opt_in, set_in_config,
                 No, Yes, No, No, NoAlias,
                 "list of symbols to use for monsters")