[FEAT]: Add Default Callbacks

[creatorfromhell]

Feature Description

These are the default callbacks that need to be implemented. The callback system has replaced TNE's use of the event system, and allows a system that is platform agnostic for addons to use without having to worry about using each platform's "reimagination" of the same old event system.

Account Callbacks

• [x] Account Load
• [x] Account Create
• [x] Account Delete

Transaction Callbacks

• [x] Pre Transaction
• [x] Post Transaction

Currency Callbacks

• [x] Currency Load
• [x] Denomination Load

Reasoning

Extendability is important.