introduce bitloops

src/main/java/puzzle/Export.java

@@ -275,13 +275,6 @@ public record Export() {
             if (letter == 0) return;
             letterAt.put(idx, (char) (64 | letter));
          });
-       /*  for (var p : placed) {
-            for (var c : p.cells) {
-               if (clues.notClue(c) && g.lisLetterAt(c)) {
-                  letterAt.put(c, (char) (64 | g.letter32At(c)));
-               }
-            }
-         }*/
          
          // 4) render gridv2 over cropped bounds (out-of-bounds become '#')
          var gridv2 = new String[Math.max(0, maxR - minR + 1)];

src/main/java/puzzle/SwedishGenerator.java

@@ -287,12 +287,6 @@ public record SwedishGenerator(Rng rng, int[] stack, Clues cache) {
       final  byte[] g;
       public long   lo, hi;
       static int offset(int r, int c) { return r | (c << 3); }
-      /// the pos will never target a clue
-      void setLetterLo(int idx, byte ch) {
-         lo |= (1L << idx);
-         
-         g[idx] = ch;
-      }
    }
    
    static record DictEntry(long[] words, long[][] posBitsets, int length, int numlong) { }