scrabble: validate scoring & move generation against real GCG games

Replay 17 real tournament games (cross-tables.com, including the 700+ club) and
check, move for move, that:
  - ScorePlay reproduces the protocol score and running total exactly;
  - the move generator produces every dictionary-valid played move with that score.

The GCG parser handles coordinates (across/down), blanks (lowercase), played-through
tiles ("."), passes/exchanges, challenge bonuses, end-game rack adjustments and phony
withdrawals ("--", un-applied). Uses the committed dawg/en_sowpods.dawg.

scrabble/testdata/anno60058.gcg

@@ -0,0 +1,47 @@
+#character-encoding UTF-8
+#player1 Caleb_Pittman Caleb Pittman
+#player2 Evan_Bialo Evan Bialo
+>Caleb_Pittman: AEEIRSY H8 AYE +12 12
+>Evan_Bialo: AMP G8 AMP +26 26
+>Caleb_Pittman: DEINRST 11A TINDERS +74 86
+#note yup
+>Evan_Bialo: EFHI A11 .HIEF +45 71
+>Caleb_Pittman: ABCFGTX I9 CAB +28 114
+#note Looks best
+>Evan_Bialo: BDGINO C9 BO.DING +28 99
+>Caleb_Pittman: ?EFGSTX 12C .EX +37 151
+#note Best
+>Evan_Bialo: UV 15C .UV +8 107
+>Caleb_Pittman: ?FGIOST J4 FOGIeST +85 236
+#note Not a word
+>Evan_Bialo: IO D8 OI +7 114
+>Caleb_Pittman: DEKNOOW E4 WOODEN +27 263
+#note Methinks best, sets up the K
+>Evan_Bialo: IQ I3 QI +26 140
+>Caleb_Pittman: IIKMRRT H4 KIR +27 290
+#note yup
+>Evan_Bialo: ?EHIOST 12I SHOrTIE +78 218
+#note 1 of 2 bingoes
+>Caleb_Pittman: EEIMRTU O12 .MEU +18 308
+#note Great
+>Evan_Bialo: AORR 4A ARRO. +18 236
+>Caleb_Pittman: EEIPRTZ A2 TR.PEZE +54 362
+#note Yep
+>Evan_Bialo: AAU C2 AU.A +8 244
+>Caleb_Pittman: AGILLTV M9 VIT.A +24 386
+#note Probably better to just play for equity, but this is fine
+>Evan_Bialo: ARW B6 WAR +40 284
+>Caleb_Pittman: AEGLLUY 1B GLEY +14 400
+#note Just tryna block
+>Evan_Bialo: CEL 2C .LEC +19 303
+>Caleb_Pittman: ADEJLNU 11K JE. +39 439
+#note Best
+>Evan_Bialo: LNNOST K4 SNOT +28 331
+#note Best
+>Caleb_Pittman: ADLNU 7E .UD +19 458
+#note I should threaten an out instead, but this is good
+>Evan_Bialo: LN 6E .N +8 339
+>Caleb_Pittman: ALN 10B L. +8 466
+#note Best
+>Evan_Bialo: L 7I L.. +4 343
+>Evan_Bialo:  (AN) +4 347