[Bleeding] Added Conversations API. Addresses BUKKIT-864

By: rmichela <deltahat@gmail.com>

paper-api/src/main/java/org/bukkit/conversations/Conversable.java

@@ -0,0 +1,42 @@
+package org.bukkit.conversations;
+
+import org.bukkit.command.CommandSender;
+
+/**
+ * The Conversable interface is used to indicate objects that can have conversations.
+ */
+public interface Conversable {
+
+    /**
+     * Tests to see of a Conversable object is actively engaged in a conversation.
+     * @return True if a conversation is in progress
+     */
+    public boolean isConversing();
+
+    /**
+     * Accepts input into the active conversation. If no conversation is in progress,
+     * this method does nothing.
+     * @param input The input message into the conversation
+     */
+    public void acceptConversationInput(String input);
+
+    /**
+     * Enters into a dialog with a Conversation object.
+     * @param conversation The conversation to begin
+     * @return True if the conversation should proceed, false if it has been enqueued
+     */
+    public boolean beginConversation(Conversation conversation);
+
+    /**
+     * Abandons an active conversation.
+     * @param conversation The conversation to abandon
+     */
+    public void abandonConversation(Conversation conversation);
+
+    /**
+     * Sends this sender a message raw
+     *
+     * @param message Message to be displayed
+     */
+    public void sendRawMessage(String message);
+}