fix #H6925 - being trapped vs Levitation/Flying

Make being trapped in/on/over floor block Levitation and Flying, the
way that being inside solid rock already does, and the way levitating
blocks flight.

Blocked levitation still provides enhanced carrying capacity since
magic is attempting to make the hero's body be bouyant.  I think that
that is appropriate but am not completely convinced.

One thing that almost certainly needs fixing is digging a hole when
trapped in the floor or tethered to a buried iron ball, where the
first part of digactualhole() releases the hero from being trapped.
If being released re-enables blocked levitation, the further stages
of digging might not make sense in some circumstances.

I recently realized that being held by a grabbing monster is similar
to being trapped so should also interfere with levitation and flying.
Nothing here attempts to address that.

Save files change, but in a compatible fashion unless trapped at the
time of saving.  If someone saves while trapped prior to this patch,
then applies it and restores, the game will behave as if the patch
wasn't in place--until escape from trap is achieved.  (Not verified.)

src/polyself.c

@@ -86,7 +86,10 @@ set_uasmon()
     PROPSET(TELEPORT, can_teleport(mdat));
     PROPSET(TELEPORT_CONTROL, control_teleport(mdat));
     PROPSET(LEVITATION, is_floater(mdat));
-    PROPSET(FLYING, is_flyer(mdat));
+    /* floating eye is the only 'floater'; it is also flagged as a 'flyer';
+       suppress flying for it so that enlightenment doesn't confusingly
+       show latent flight capability always blocked by levitation */
+    PROPSET(FLYING, (is_flyer(mdat) && !is_floater(mdat)));
     PROPSET(SWIMMING, is_swimmer(mdat));
     /* [don't touch MAGICAL_BREATHING here; both Amphibious and Breathless
        key off of it but include different monster forms...] */
@@ -116,12 +119,21 @@ set_uasmon()
 void
 float_vs_flight()
 {
-    /* floating overrides flight; normally float_up() and float_down()
-       handle this, but sometimes they're skipped */
-    if (HLevitation || ELevitation)
+    boolean stuck_in_floor = (u.utrap && u.utraptype != TT_PIT);
+
+    /* floating overrides flight; so does being trapped in the floor */
+    if ((HLevitation || ELevitation)
+        || ((HFlying || EFlying) && stuck_in_floor))
         BFlying |= I_SPECIAL;
     else
         BFlying &= ~I_SPECIAL;
+    /* being trapped on the ground (bear trap, web, molten lava survived
+       with fire resistance, former lava solidified via cold, tethered
+       to a buried iron ball) overrides floating--the floor is reachable */
+    if ((HLevitation || ELevitation) && stuck_in_floor)
+        BLevitation |= I_SPECIAL;
+    else
+        BLevitation &= ~I_SPECIAL;
     context.botl = TRUE;
 }
 
@@ -207,8 +219,8 @@ const char *fmt, *arg;
     if (u.twoweap && !could_twoweap(youmonst.data))
         untwoweapon();
 
-    if (u.utraptype == TT_PIT && u.utrap) {
-        u.utrap = rn1(6, 2); /* time to escape resets */
+    if (u.utrap && u.utraptype == TT_PIT) {
+        set_utrap(rn1(6, 2), TT_PIT); /* time to escape resets */
     }
     if (was_blind && !Blind) { /* reverting from eyeless */
         Blinded = 1L;
@@ -725,8 +737,8 @@ int mntmp;
     drop_weapon(1);
     (void) hideunder(&youmonst);
 
-    if (u.utraptype == TT_PIT && u.utrap) {
-        u.utrap = rn1(6, 2); /* time to escape resets */
+    if (u.utrap && u.utraptype == TT_PIT) {
+        set_utrap(rn1(6, 2), TT_PIT); /* time to escape resets */
     }
     if (was_blind && !Blind) { /* previous form was eyeless */
         Blinded = 1L;
@@ -794,17 +806,17 @@ int mntmp;
         spoteffects(TRUE);
     if (Passes_walls && u.utrap
         && (u.utraptype == TT_INFLOOR || u.utraptype == TT_BURIEDBALL)) {
-        u.utrap = 0;
-        if (u.utraptype == TT_INFLOOR)
+        if (u.utraptype == TT_INFLOOR) {
             pline_The("rock seems to no longer trap you.");
-        else {
+        } else {
             pline_The("buried ball is no longer bound to you.");
             buried_ball_to_freedom();
         }
+        reset_utrap(TRUE);
     } else if (likes_lava(youmonst.data) && u.utrap
                && u.utraptype == TT_LAVA) {
-        u.utrap = 0;
         pline_The("%s now feels soothing.", hliquid("lava"));
+        reset_utrap(TRUE);
     }
     if (amorphous(youmonst.data) || is_whirly(youmonst.data)
         || unsolid(youmonst.data)) {
@@ -823,11 +835,11 @@ int mntmp;
         You("are no longer stuck in the %s.",
             u.utraptype == TT_WEB ? "web" : "bear trap");
         /* probably should burn webs too if PM_FIRE_ELEMENTAL */
-        u.utrap = 0;
+        reset_utrap(TRUE);
     }
     if (webmaker(youmonst.data) && u.utrap && u.utraptype == TT_WEB) {
         You("orient yourself on the web.");
-        u.utrap = 0;
+        reset_utrap(TRUE);
     }
     check_strangling(TRUE); /* maybe start strangling */