DEV-1761: New rules API (#118)

* DEV-1761: Clean up Ruleset interface (#115)

* remove legacy ruleset types and simplify ruleset interface

* remove unnecessary settings argument from Ruleset interface

* decouple rules.Settings from client API and store settings as strings

* DEV 1761: Add new BoardState and Point fields (#117)

* add Point.TTL, Point.Value, GameState and PointState to BoardState

* allow maps to access BoardState.GameState,PointState

* add PreUpdateBoard and refactor snail_mode with it

* fix bug where an extra turn was printed to the console

* fix formatting

* fix lint errors

Co-authored-by: JonathanArns <jonathan.arns@googlemail.com>

settings.go

@@ -0,0 +1,90 @@
+package rules
+
+import "strconv"
+
+// Settings contains all settings relevant to a game.
+// The settings are stored as raw string values, which should not be accessed
+// directly. Calling code should instead use the Int/Bool methods to parse them.
+type Settings struct {
+	rawValues map[string]string
+
+	rand Rand
+	seed int64
+}
+
+func NewSettings(params map[string]string) Settings {
+	rawValues := make(map[string]string, len(params))
+
+	// Copy incoming params into a new map
+	for key, value := range params {
+		rawValues[key] = value
+	}
+
+	return Settings{
+		rawValues: rawValues,
+	}
+}
+
+func NewSettingsWithParams(params ...string) Settings {
+	rawValues := map[string]string{}
+
+	for index := 1; index < len(params); index += 2 {
+		rawValues[params[index-1]] = params[index]
+	}
+
+	return Settings{
+		rawValues: rawValues,
+	}
+}
+
+// Get a random number generator initialized based on the seed and current turn.
+func (settings Settings) GetRand(turn int) Rand {
+	// Allow overriding the random generator for testing
+	if settings.rand != nil {
+		return settings.rand
+	}
+
+	if settings.seed != 0 {
+		return NewSeedRand(settings.seed + int64(turn))
+	}
+
+	// Default to global random number generator if neither seed or rand are set.
+	return GlobalRand
+}
+
+func (settings Settings) WithRand(rand Rand) Settings {
+	settings.rand = rand
+	return settings
+}
+
+func (settings Settings) Seed() int64 {
+	return settings.seed
+}
+
+func (settings Settings) WithSeed(seed int64) Settings {
+	settings.seed = seed
+	return settings
+}
+
+// Bool returns the boolean value for the specified parameter.
+// If the parameter doesn't exist, the default value will be returned.
+// If the parameter does exist, but is not "true", false will be returned.
+func (settings Settings) Bool(paramName string, defaultValue bool) bool {
+	if val, ok := settings.rawValues[paramName]; ok {
+		return val == "true"
+	}
+	return defaultValue
+}
+
+// Int returns the int value for the specified parameter.
+// If the parameter doesn't exist, the default value will be returned.
+// If the parameter does exist, but is not a valid int, the default value will be returned.
+func (settings Settings) Int(paramName string, defaultValue int) int {
+	if val, ok := settings.rawValues[paramName]; ok {
+		i, err := strconv.Atoi(val)
+		if err == nil {
+			return i
+		}
+	}
+	return defaultValue
+}