water description

The wall of water goaded me into updating waterbody_name().  It's
mostly the same, aside from being moved from mkmaze.c to pager.c and
adding "{wall of|limitless} water" instead of plain "water" for WATER
terrain.  I'm not very happy with "limitless" for the Plane of Water
because limits imposed by air bubbles are all over the place.  "Wall
of water" might work ok for that level.

Water on Medusa's level is now described as "shallow sea" rather than
lame "water".  The two unusual pools on the Samurai home level are
described as "pond" rather than previous "water" which replaced 3.6's
ridiculous "moat".  When lava is hallucinated, it is described as
"molten <substance>" (yielding silly things like "molten yoghurt"),
rather than just "<substance>" to distinguish it from hallucinated
water.  'autodescribe' doesn't use waterbody_name() though.

include/extern.h

@@ -1350,7 +1350,6 @@ extern void movebubbles(void);
 extern void water_friction(void);
 extern void save_waterlevel(NHFILE *);
 extern void restore_waterlevel(NHFILE *);
-extern const char *waterbody_name(xchar, xchar);
 
 /* ### mkobj.c ### */
 
@@ -1934,6 +1933,7 @@ extern char *self_lookat(char *);
 extern char *monhealthdescr(struct monst *mon, boolean, char *);
 extern void mhidden_description(struct monst *, boolean, char *);
 extern boolean object_from_map(int,int,int,struct obj **);
+extern const char *waterbody_name(xchar, xchar);
 extern int do_screen_description(coord, boolean, int, char *, const char **,
                                  struct permonst **);
 extern int do_look(int, coord *);