Port Area plugin to Kotlin

game/plugin/areas/src/action.kt

@@ -0,0 +1,18 @@
+package org.apollo.game.plugins.area
+
+/**
+ * Defines an area action using the DSL.
+ */
+fun action(@Suppress("UNUSED_PARAMETER") name: String, builder: ActionBuilder.() -> Unit) {
+    val listener = ActionBuilder()
+    builder(listener)
+
+    actions.add(listener.build())
+}
+
+/**
+ * The [Set] of ([Area], [AreaAction]) [Pair]s.
+ */
+val actions = mutableSetOf<Pair<Area, AreaAction>>()
+
+class AreaAction(val entrance: AreaListener, val inside: AreaListener, val exit: AreaListener)