Add tabletop components 486-500 and ten game icons

Fifteen pieces of a games night: Dice, DiceTray, PlayingCard, CardHand,
Deck, Chessboard, GoBoard, MahjongTile, Domino, Roulette, CoinFlip,
BingoCard, TicTacToe, ScoreTrack and Meeple. Component number 500 is
a meeple, which seems right.

Dice tumble, coins turn and wheels spin on a cue, a frame at a time,
and land at once under Reduce Motion. Hands lift the card you point
at and play the one drawn on top; pieces and stones pick the lighter
of Lit and Ink for White, so they read in every palette; the computer
plays a fair O; FREE is a star in every language.

New 12x12 icons: Spade, Club, Diamond, Meeple, King, Queen, Rook,
Bishop, Knight and Pawn.

gallery/tabletop_demo_test.go

@@ -0,0 +1,45 @@
+package gallery
+
+import (
+	"strconv"
+	"strings"
+	"testing"
+)
+
+func TestTabletopDemosLogTheirActions(t *testing.T) {
+	// Focusing, or a move that ends nothing, logs nothing.
+	quiet := map[string]bool{"key:Right": true}
+	for _, tc := range []struct {
+		path  string
+		steps []string
+	}{
+		{"/c/486-dice", []string{"ROLL"}}, {"/c/487-dicetray", []string{"ROLL ALL"}},
+		{"/c/489-cardhand", []string{"Hand", "DEAL"}}, {"/c/490-deck", []string{"Draw pile"}},
+		{"/c/491-chessboard", []string{"square:52", "NEW GAME"}}, {"/c/492-goboard", []string{"Goban"}},
+		{"/c/495-roulette", []string{"SPIN"}}, {"/c/496-coinflip", []string{"FLIP"}},
+		{"/c/497-bingocard", []string{"Card", "key:Right", "key:Enter"}}, {"/c/498-tictactoe", []string{"Grid"}},
+		{"/c/499-scoretrack", []string{"TAKE A TURN"}},
+	} {
+		a, tt := open(tc.path)
+		slug := tc.path[3:]
+		for _, step := range tc.steps {
+			before := len(a.logs[slug])
+			if k, ok := strings.CutPrefix(step, "key:"); ok {
+				tt.Key(0, letters[k])
+			} else if sq, ok := strings.CutPrefix(step, "square:"); ok {
+				// A chess square: 16 dots, two pixels a dot.
+				r, ok := tt.Find("CHESSBOARD")
+				i, err := strconv.Atoi(sq)
+				if !ok || err != nil {
+					t.Fatalf("no board, or square %q: %v", sq, err)
+				}
+				tt.ClickAt(r.X+float32(32*(i%8)+16), r.Y+float32(32*(i/8)+16))
+			} else {
+				click(t, tt, step)
+			}
+			if len(a.logs[slug]) <= before && !quiet[step] && step != "Card" {
+				t.Errorf("%s: %s logged nothing: %q", slug, step, a.logs[slug])
+			}
+		}
+	}
+}