bubble/cloud save/restore overhaul

The air bubbles on the Plane of Water and the clouds on the Plane of
Air were being saved and restored as part of the current level's state
(which is the 'u' struct and invent and such) rather than with the
current level itself.  That was ok for normal play, but for wizard
mode's ^V allowing you to return to a previously visited endgame level
after moving to a different one it meant a new set of bubbles for
Water and new set of clouds for Air.  Even that was ok since it only
applied to wizard mode, but using #wizmakemap to recreate Water or Air
while you were on it added a new set of bubbles or clouds to the
existing ones.  If repeated, eventually there wouldn't be much water
or air left.

Instead of just adding a hack to #wizmakemap, change save/restore to
keep the bubbles/clouds with the level rather than with the state.
That wasn't trivial and now I know why the old odd arrangement was
chosen.  Saving hides u.uz by zeroing it out for levels that the hero
isn't on and it is zero during restore so simple checks for whether a
given level is water or air won't work.

This also adds another non-file/non-debugpline() use of DEBUGFILES:
 DEBUGFILES=seethru nethack -D
will make water and clouds be transparent instead of opaque.  It also
makes fumaroles and other light-blocking gas clouds be transparent
which wasn't really intended, but avoiding it would be extra work that
doesn't accomplish much.

Increments EDITLEVEL for the third time this week....

src/save.c

@@ -19,6 +19,7 @@ int dotcnt, dotrow; /* also used in restore */
 static void savelevchn(NHFILE *);
 static void savelevl(NHFILE *,boolean);
 static void savedamage(NHFILE *);
+static void save_bubbles(NHFILE *, xchar);
 static void save_stairs(NHFILE *);
 static void saveobj(NHFILE *,struct obj *);
 static void saveobjchn(NHFILE *,struct obj **);
@@ -27,6 +28,7 @@ static void savemonchn(NHFILE *,struct monst *);
 static void savetrapchn(NHFILE *,struct trap *);
 static void save_gamelog(NHFILE *);
 static void savegamestate(NHFILE *);
+static void savelev_core(NHFILE *, xchar);
 static void save_msghistory(NHFILE *);
 
 #ifdef ZEROCOMP
@@ -76,7 +78,6 @@ dosave0(void)
 {
     const char *fq_save;
     xchar ltmp;
-    d_level uz_save;
     char whynot[BUFSZ];
     NHFILE *nhfp, *onhfp;
     int res = 0;
@@ -174,8 +175,9 @@ dosave0(void)
      * parts of the restore code from completely initializing all
      * in-core data structures, since all we're doing is copying.
      * This also avoids at least one nasty core dump.
+     * [g.uz_save is used by save_bubbles() as well as to restore u.uz]
      */
-    uz_save = u.uz;
+    g.uz_save = u.uz;
     u.uz.dnum = u.uz.dlevel = 0;
     /* these pointers are no longer valid, and at least u.usteed
      * may mislead place_monster() on other levels
@@ -184,7 +186,7 @@ dosave0(void)
     u.usteed = (struct monst *) 0;
 
     for (ltmp = (xchar) 1; ltmp <= maxledgerno(); ltmp++) {
-        if (ltmp == ledger_no(&uz_save))
+        if (ltmp == ledger_no(&g.uz_save))
             continue;
         if (!(g.level_info[ltmp].flags & LFILE_EXISTS))
             continue;
@@ -218,7 +220,8 @@ dosave0(void)
     }
     close_nhfile(nhfp);
 
-    u.uz = uz_save;
+    u.uz = g.uz_save;
+    g.uz_save.dnum = g.uz_save.dlevel = 0;
 
     /* get rid of current level --jgm */
     delete_levelfile(ledger_no(&u.uz));
@@ -349,7 +352,6 @@ savegamestate(NHFILE* nhfp)
     }
     savefruitchn(nhfp);
     savenames(nhfp);
-    save_waterlevel(nhfp);
     save_msghistory(nhfp);
     save_gamelog(nhfp);
     if (nhfp->structlevel)
@@ -457,6 +459,27 @@ savestateinlock(void)
 
 void
 savelev(NHFILE *nhfp, xchar lev)
+{
+    boolean set_uz_save = (g.uz_save.dnum == 0 && g.uz_save.dlevel == 0);
+
+    /* caller might have already set up g.uz_save and zeroed u.uz;
+       if not, we need to set it for save_bubbles() */
+    if (set_uz_save) {
+        if (u.uz.dnum == 0 && u.uz.dlevel == 0) {
+            g.program_state.something_worth_saving = 0;
+            panic("savelev: where are we?");
+        }
+        g.uz_save = u.uz;
+    }
+
+    savelev_core(nhfp, lev);
+
+    if (set_uz_save)
+        g.uz_save.dnum = g.uz_save.dlevel = 0; /* unset */
+}
+
+static void
+savelev_core(NHFILE *nhfp, xchar lev)
 {
 #ifdef TOS
     short tlev;
@@ -544,6 +567,8 @@ savelev(NHFILE *nhfp, xchar lev)
     save_engravings(nhfp);
     savedamage(nhfp); /* pending shop wall and/or floor repair */
     save_regions(nhfp);
+    save_bubbles(nhfp, lev); /* for water and air */
+
     if (nhfp->mode != FREEING) {
         if (nhfp->structlevel)
             bflush(nhfp->fd);
@@ -618,6 +643,28 @@ savelevl(NHFILE* nhfp, boolean rlecomp)
     return;
 }
 
+/* save Plane of Water's air bubbles and Plane of Air's clouds */
+static void
+save_bubbles(NHFILE *nhfp, xchar lev)
+{
+    xchar bbubbly;
+
+    /* air bubbles and clouds used to be saved as part of game state
+       because restoring them needs dungeon data that isn't available
+       during the first pass of their levels; now that they are part of
+       the current level instead, we write a zero or non-zero marker
+       so that restore can determine whether they are present even when
+       u.uz and ledger_no() aren't available to it yet */
+    bbubbly = 0;
+    if (lev == ledger_no(&water_level) || lev == ledger_no(&air_level))
+        bbubbly = lev; /* non-zero */
+    if (nhfp->structlevel)
+        bwrite(nhfp->fd, (genericptr_t) &bbubbly, sizeof bbubbly);
+
+    if (bbubbly)
+        save_waterlevel(nhfp); /* save air bubbles or clouds */
+}
+
 /* used when saving a level and also when saving dungeon overview data */
 void
 savecemetery(NHFILE* nhfp, struct cemetery** cemeteryaddr)