Patch from James H to abstract out of Dominosa the code which

randomly generates a tiling of a rectangle with dominoes, since he
wants to reuse that function in another puzzle.

[originally from svn r8488]

puzzles.h

@@ -338,6 +338,12 @@ void edsf_merge(int *dsf, int v1, int v2, int inverse);
 void dsf_merge(int *dsf, int v1, int v2);
 void dsf_init(int *dsf, int len);
 
+/*
+ * laydomino.c
+ */
+int *domino_layout(int w, int h, random_state *rs);
+void domino_layout_prealloc(int w, int h, random_state *rs,
+                            int *grid, int *grid2, int *list);
 /*
  * version.c
  */