Rename Fish to FishHook. Fixes BUKKIT-3856

"Fish" is a badly named class to represent a fishing hook due to the
possibility (or lack of) that Minecraft may be getting fish entities.

This commit provides potential future compatibility by deprecating the
existing Fish class and moving the methods to a new class: FishHook.

src/main/java/org/bukkit/entity/Fish.java

@@ -2,28 +2,7 @@ package org.bukkit.entity;
 
 /**
  * Represents a fishing hook.
+ * @deprecated in favor of {@link FishHook}
  */
-public interface Fish extends Projectile {
-
-    /**
-     * Gets the chance of a fish biting.
-     * <p>
-     * 0.0 = No Chance.<br>
-     * 1.0 = Instant catch.
-     *
-     * @return chance the bite chance
-     */
-    public double getBiteChance();
-
-    /**
-     * Sets the chance of a fish biting.
-     * <p>
-     * 0.0 = No Chance.<br>
-     * 1.0 = Instant catch.
-     *
-     * @param chance the bite chance
-     * @throws IllegalArgumentException if the bite chance is not between 0
-     *     and 1
-     */
-    public void setBiteChance(double chance) throws IllegalArgumentException;
+public interface Fish extends FishHook {
 }

src/main/java/org/bukkit/entity/FishHook.java

@@ -0,0 +1,28 @@
+package org.bukkit.entity;
+
+/**
+ * Represents a fishing hook.
+ */
+public interface FishHook extends Projectile {
+    /**
+     * Gets the chance of a fish biting.
+     * <p>
+     * 0.0 = No Chance.<br>
+     * 1.0 = Instant catch.
+     *
+     * @return chance the bite chance
+     */
+    public double getBiteChance();
+
+    /**
+     * Sets the chance of a fish biting.
+     * <p>
+     * 0.0 = No Chance.<br>
+     * 1.0 = Instant catch.
+     *
+     * @param chance the bite chance
+     * @throws IllegalArgumentException if the bite chance is not between 0
+     *     and 1
+     */
+    public void setBiteChance(double chance) throws IllegalArgumentException;
+}