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/anno54854.gcg

@@ -0,0 +1,29 @@
+#character-encoding UTF-8
+#player1 David_Firstman David Firstman
+#player2 Zombywoof Zombywoof
+>David_Firstman: CEIOPRS 8D COPIERS +78 78
+>Zombywoof: AAELORW D8 .LAWER +22 22
+>David_Firstman: ?AEGILT H8 .GALITEs +77 155
+>Zombywoof: AABDFGO G12 GAB +17 39
+>David_Firstman: AIJNOUY J6 JU. +26 181
+>Zombywoof: AADFHOR C10 FARAD +34 73
+>David_Firstman: AINOSVY 15H .YNOVIAS +101 282
+>Zombywoof: EEHKNOO 10F KO. +17 90
+>David_Firstman: ?EHINSX E11 EX +40 322
+>Zombywoof: EEHNOQT K5 HON +23 113
+>David_Firstman: ?HIINPS O8 kINSHIP. +98 420
+>Zombywoof: EEEQTTV B13 VET +24 137
+>David_Firstman: DMNORUW L4 MOW +34 454
+>Zombywoof: EEOOQTT M2 TOOT +18 155
+>David_Firstman: ACDENRU 2H UNCRA.ED +84 538
+>Zombywoof: EEFLQTZ G7 Q. +21 176
+>David_Firstman: AABEMOT 1H MA +26 564
+>Zombywoof: EEFLTUZ 1N FE +29 205
+>David_Firstman: ABDEORT 3B ABORTED +78 642
+>Zombywoof: ELLSTUZ 11J LUTZE. +30 235
+>David_Firstman: EENNRUY 4A EYEN +29 671
+>Zombywoof: DGIIILS A14 GI +20 255
+>David_Firstman: EINRU M11 .IN +24 695
+>Zombywoof: DIILS 2A ID +20 275
+>David_Firstman: ERU F3 .RUE +6 701
+>David_Firstman:  (ILS) +6 707