Improves comments for Stargate events, and adds a new event for teleporting entities

Adds information about what events can be used for
Tries to clarify event comments where possible
Renames The StargatePortalEvent to StargatePlayerPortalEvent
Adds StargateEntityPortalEvent
Makes the StargateEntityPortalEvent trigger whenever a vehicle is teleported
Removes the unused event name for all events

src/main/java/net/knarcraft/stargate/event/StargatePlayerPortalEvent.java

@@ -0,0 +1,76 @@
+package net.knarcraft.stargate.event;
+
+import net.knarcraft.stargate.portal.Portal;
+import org.bukkit.Location;
+import org.bukkit.entity.Player;
+import org.bukkit.event.HandlerList;
+import org.jetbrains.annotations.NotNull;
+
+/**
+ * This event should be called whenever a player teleports through a stargate
+ *
+ * <p>This event can be used to overwrite the location the player is teleported to.</p>
+ */
+@SuppressWarnings("unused")
+public class StargatePlayerPortalEvent extends StargatePlayerEvent {
+
+    private static final HandlerList handlers = new HandlerList();
+    private final Portal destination;
+    private Location exit;
+
+    /**
+     * Instantiates a new stargate player portal event
+     *
+     * @param player      <p>The player teleporting</p>
+     * @param portal      <p>The portal the player entered from</p>
+     * @param destination <p>The destination the player should exit from</p>
+     * @param exit        <p>The exit location of the destination portal the user will be teleported to</p>
+     */
+    public StargatePlayerPortalEvent(Player player, Portal portal, Portal destination, Location exit) {
+        super(portal, player);
+
+        this.destination = destination;
+        this.exit = exit;
+    }
+
+    /**
+     * Return the destination portal
+     *
+     * @return <p>The destination portal</p>
+     */
+    public Portal getDestination() {
+        return destination;
+    }
+
+    /**
+     * Return the location of the players exit point
+     *
+     * @return <p>Location of the exit point</p>
+     */
+    public Location getExit() {
+        return exit;
+    }
+
+    /**
+     * Set the location of the player's exit point
+     */
+    public void setExit(Location location) {
+        this.exit = location;
+    }
+
+    /**
+     * Gets a handler-list containing all event handlers
+     *
+     * @return <p>A handler-list with all event handlers</p>
+     */
+    public static HandlerList getHandlerList() {
+        return handlers;
+    }
+
+    @Override
+    @NotNull
+    public HandlerList getHandlers() {
+        return handlers;
+    }
+
+}