Implemented Death Plateau quest

Server/src/main/core/api/ContentAPI.kt

@@ -1363,6 +1363,17 @@ fun setInterfaceText(player: Player, string: String, iface: Int, child: Int) {
     player.packetDispatch.sendString(string, iface, child)
 }
 
+/**
+ * Allows you to hide or show specific children in an interface
+ * @param player the player to send the packet to
+ * @param iface the ID of the interface to use
+ * @param child the index of the child to hide or show
+ * @param hide if the child should be hidden or not
+ */
+fun setComponentVisibility(player: Player, iface: Int, child: Int, hide: Boolean) {
+    player.packetDispatch.sendInterfaceConfig(iface, child, hide)
+}
+
 /**
  * Closes any open (non-chat) interfaces for the player
  * @param player the player to close the interface for
@@ -1579,6 +1590,13 @@ fun setQuestStage(player: Player, quest: String, stage: Int) {
     player.questRepository.syncronizeTab(player)
 }
 
+/**
+ * Check if a quest is in progress
+ */
+fun isQuestInProgress(player: Player, quest: String, startStage: Int, endStage: Int): Boolean {
+    return player.questRepository.getStage(quest) in startStage..endStage
+}
+
 /**
  * Check if a quest is complete
  */