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/restore.c

@@ -30,6 +30,7 @@ static void ghostfruit(struct obj *);
 static boolean restgamestate(NHFILE *, unsigned int *, unsigned int *);
 static void restlevelstate(unsigned int, unsigned int);
 static int restlevelfile(xchar);
+static void rest_bubbles(NHFILE *);
 static void restore_gamelog(NHFILE *);
 static void restore_msghistory(NHFILE *);
 static void reset_oattached_mids(boolean);
@@ -683,7 +684,6 @@ restgamestate(NHFILE* nhfp, unsigned int* stuckid, unsigned int* steedid)
     g.ffruit = loadfruitchn(nhfp);
 
     restnames(nhfp);
-    restore_waterlevel(nhfp);
     restore_msghistory(nhfp);
     restore_gamelog(nhfp);
     /* must come after all mons & objs are restored */
@@ -1127,6 +1127,7 @@ getlev(NHFILE* nhfp, int pid, xchar lev)
     }
     restdamage(nhfp);
     rest_regions(nhfp);
+    rest_bubbles(nhfp); /* for water and air; empty marker on other levels */
 
     if (ghostly) {
         stairway *stway = g.stairs;
@@ -1217,6 +1218,23 @@ get_plname_from_file(NHFILE* nhfp, char *plbuf)
     return;
 }
 
+/* restore Plane of Water's air bubbles and Plane of Air's clouds */
+static void
+rest_bubbles(NHFILE *nhfp)
+{
+    xchar bbubbly;
+
+    /* whether or not the Plane of Water's air bubbles or Plane of Air's
+       clouds are present is recorded during save so that we don't have to
+       know what level is being restored */
+    bbubbly = 0;
+    if (nhfp->structlevel)
+        mread(nhfp->fd, (genericptr_t) &bbubbly, sizeof bbubbly);
+
+    if (bbubbly)
+        restore_waterlevel(nhfp);
+}
+
 static void
 restore_gamelog(NHFILE* nhfp)
 {