Packets are sent out when collision happens and receiver is able to interpret and display as visual alert. Updated visual alert to looks better.

- Created yacht event code message to be sent out as packet.
- Added observers to main server thread on yacht so when collision detected, main server thread will send out yacht event message to all server to client threads.
- Updated collision visual alert using circle and animation timer.

#story[1117]

src/main/java/seng302/gameServer/server/messages/YachtEventCodeMessage.java

@@ -0,0 +1,52 @@
+package seng302.gameServer.server.messages;
+
+/**
+ * Created by zyt10 on 10/08/17.
+ */
+public class YachtEventCodeMessage extends Message {
+
+    private final MessageType MESSAGE_TYPE = MessageType.YACHT_EVENT_CODE;
+    private final int MESSAGE_VERSION = 1; //Always set to 1
+    private final int MESSAGE_SIZE = 22;
+
+    // Message fields
+    private long timeStamp;
+    private long ack = 0x00; //Unused
+    private int raceId;
+    private int destSourceId;
+    private int incidentId;
+    private int eventId;
+
+
+    public YachtEventCodeMessage(Integer subjectId) {
+        timeStamp = System.currentTimeMillis() / 1000L;
+        ack = 0;
+        raceId = 1;
+        destSourceId = subjectId;  // collision boat source id
+        incidentId = 0;
+        eventId = 33;
+
+        setHeader(new Header(MESSAGE_TYPE, 0x01, (short) getSize()));
+        allocateBuffer();
+        writeHeaderToBuffer();
+
+        // Write message fields
+        putUnsignedByte((byte) MESSAGE_VERSION);
+        putInt((int) timeStamp, 6);
+        putInt((int) ack, 2);
+        putInt((int) raceId, 4);
+        putInt((int) destSourceId, 4);
+        putInt((int) incidentId, 4);
+        putInt((int) eventId, 1);
+
+        writeCRC();
+        rewind();
+    }
+
+    /**
+     * @return The length of this message
+     */
+    public int getSize() {
+        return MESSAGE_SIZE;
+    }
+}