fix #H1232 - hole in ice is described as moat [1 of 2] (trunk only)

fix #H1232 - hole in ice is described as moat [1 of 2] (trunk only)

     From a bug report, when ice on the Valkyrie
quest home level was melted and a boulder filled the resulting pool, that
pool was described as a moat.  This was actually a terrain issue rather
than a formatting glitch, so instead of tweaking waterbody_name() with an
extra special case, extend the level compiler to allow specifying ice as
frozen pool instead of always being frozen moat.  There's no provision
for having both types of ice on the same level, just a level-wide flag to
control which of the two applies for ice on that level.

     This change has a side-effect for the V quest levels:  once ice has
been melted, a second blast of fire will now boil away the pool and leave
a pit.  The unfrozen water locations on the home level already behaved
that way (ie, they are pools rather than moats) so this should be ok.  I
also added <Someone>'s suggestion to make one of the two drawbridges
on the goal level start in random state instead of always being open.