Castle Wall Hazard Map (#101)

* castle_wall map

Wall of hazards around the board with dangerous bridges.

- add support for all standard board sizes
- hazard placement for all board sizes

* passage food placement for all board sizes

* 4 snake starting positions for all maps

* only one food can spawn on a bridge

* support 8 snakes for all board sizes

support 12 snakes on XLarge and XXLarge board sizes

* max 2 food sm/med/lg and max 4 food on xlg/xxlg

no food in the first 10 turns

* sort generated hazard positions

* remove 'uninteresting' castle wall map board sizes

* refactor castle wall map to align with #103

* align map castle wall meta Name with ID

* set MinPlayers to 1 for castle wall map

* pass max snake/food and startPosition to priv func

* fix castle wall food placement and refactor tests

* avoid food spawn by snake heads on castle wall map

- fixes forced food spawning infront of snake issue on large & xlarge maps with double walls

maps/castle_wall_test.go

@@ -0,0 +1,42 @@
+package maps_test
+
+import (
+	"testing"
+
+	"github.com/BattlesnakeOfficial/rules"
+	"github.com/BattlesnakeOfficial/rules/maps"
+	"github.com/stretchr/testify/require"
+)
+
+func TestCastleWallHazardsMap(t *testing.T) {
+	// check error handling
+	m := maps.CastleWallMediumHazardsMap{}
+	settings := rules.Settings{}
+
+	// check error for unsupported board sizes
+	state := rules.NewBoardState(7, 7)
+	editor := maps.NewBoardStateEditor(state)
+	err := m.SetupBoard(state, settings, editor)
+	require.Error(t, err)
+
+	tests := []struct {
+		Map    maps.GameMap
+		Width  uint
+		Height uint
+	}{
+		{maps.CastleWallMediumHazardsMap{}, 11, 11},
+		{maps.CastleWallLargeHazardsMap{}, 19, 19},
+		{maps.CastleWallExtraLargeHazardsMap{}, 25, 25},
+	}
+
+	// check all the supported sizes
+	for _, test := range tests {
+		state = rules.NewBoardState(int(test.Width), int(test.Height))
+		state.Snakes = append(state.Snakes, rules.Snake{ID: "1", Body: []rules.Point{}})
+		editor = maps.NewBoardStateEditor(state)
+		require.Empty(t, state.Hazards)
+		err = test.Map.SetupBoard(state, settings, editor)
+		require.NoError(t, err)
+		require.NotEmpty(t, state.Hazards)
+	}
+}