Add a way to detect when fishing was successful via scripting APIs

With the current scripting APIs there is no way to detect if a fishing attempt was successful. This could be extremely useful for fishing add-ons. For example: Say you have added custom loot to a fishing loot table and want to announce to the server when the rarest item is caught. There's no way to do that. Another example would be creating an MMO/RPG style add-on. If you were creating custom skill levels, it would not be possible to have fishing as one of those without creating a custom item to add to the loot table which would have to be used to have the XP granted.