[12623] Simplify and add comments to new stats system code.

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Автор: Schmoozerd


<pre style='white-space:pre-wrap;width:81ex'>[12623] Simplify and add comments to new stats system code.</pre>


Подробнее... (https://github.com/cmangos/mangos-wotlk/commit/e08662f87f3b3974de1c9425d6ea0969e07da910)