Document hard mode in Slant, and also fix an obvious memory

management error in game_configure().

[originally from svn r6169]

puzzles.but

@@ -1485,6 +1485,17 @@ These parameters are available from the \q{Custom...} option on the
 
 \dd Size of grid in squares.
 
+\dt \e{Difficulty}
+
+\dd Controls the difficulty of the generated puzzle. At Hard level,
+you are required to do deductions based on knowledge of
+\e{relationships} between squares rather than always being able to
+deduce the exact contents of one square at a time. (For example, you
+might know that two squares slant in the same direction, even if you
+don't yet know what that direction is, and this might enable you to
+deduce something about still other squares.) Even at Hard level,
+guesswork and backtracking should never be necessary.
+
 
 \C{lightup} \i{Light Up}
 

slant.c

@@ -171,7 +171,7 @@ static config_item *game_configure(game_params *params)
     config_item *ret;
     char buf[80];
 
-    ret = snewn(2, config_item);
+    ret = snewn(4, config_item);
 
     ret[0].name = "Width";
     ret[0].type = C_STRING;